全文获取类型
收费全文 | 14912篇 |
免费 | 1125篇 |
国内免费 | 430篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 212篇 |
妇产科学 | 99篇 |
基础医学 | 2000篇 |
口腔科学 | 302篇 |
临床医学 | 1080篇 |
内科学 | 2251篇 |
皮肤病学 | 184篇 |
神经病学 | 853篇 |
特种医学 | 572篇 |
外科学 | 1016篇 |
综合类 | 1600篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 2012篇 |
眼科学 | 137篇 |
药学 | 2603篇 |
6篇 | |
中国医学 | 750篇 |
肿瘤学 | 689篇 |
出版年
2023年 | 169篇 |
2022年 | 400篇 |
2021年 | 547篇 |
2020年 | 473篇 |
2019年 | 425篇 |
2018年 | 442篇 |
2017年 | 452篇 |
2016年 | 459篇 |
2015年 | 484篇 |
2014年 | 816篇 |
2013年 | 929篇 |
2012年 | 720篇 |
2011年 | 784篇 |
2010年 | 580篇 |
2009年 | 583篇 |
2008年 | 545篇 |
2007年 | 514篇 |
2006年 | 500篇 |
2005年 | 582篇 |
2004年 | 490篇 |
2003年 | 519篇 |
2002年 | 383篇 |
2001年 | 351篇 |
2000年 | 291篇 |
1999年 | 291篇 |
1998年 | 296篇 |
1997年 | 279篇 |
1996年 | 213篇 |
1995年 | 225篇 |
1994年 | 179篇 |
1993年 | 180篇 |
1992年 | 151篇 |
1991年 | 150篇 |
1990年 | 128篇 |
1989年 | 135篇 |
1988年 | 134篇 |
1987年 | 121篇 |
1986年 | 124篇 |
1985年 | 151篇 |
1984年 | 145篇 |
1983年 | 100篇 |
1982年 | 123篇 |
1981年 | 119篇 |
1980年 | 114篇 |
1979年 | 116篇 |
1978年 | 109篇 |
1977年 | 84篇 |
1976年 | 69篇 |
1975年 | 41篇 |
1974年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Zusammenfassung Die wichtigsten Vertreter der hormonal aktiven Ovarialtumoren sind in der Gruppe der Keimstrang-Stromatumoren zusammengefasst. Sie machen weniger als 5% der Ovarialgeschwülste aus. Die Mehrzahl der Keimstrang-Stromatumoren besitzt die Fähigkeit zur Biosynthese von Steroidhormonen. Die pathologische Hormonbildung bewirkt spezifische Effekte an den hormonsensitiven Organen. Die klinischen Befunde sind abhängig von Art und Intensität der Hormonproduktion und vom Lebensalter der Patientin. In der Dignität stehen die Keimstrang-Stromatumoren als fakultativ maligne Geschwülste zwischen den nichtinvasiven (Borderline-) und den invasiven epithelialen Tumoren des Ovars. Neben den speziellen zur Hormonbiosynthese befähigten Ovarialgeschwülsten (Keimstrang-Stromatumoren, Steroidzelltumoren) können benigne und maligne Ovarialtumoren verschiedenen Typs aufgrund einer Vermehrung und/oder Stimulation von nicht-neoplastischen Zellen im Ovarialstroma endokrine (östrogene oder androgene) Aktivität aufweisen.
相似文献
相似文献
142.
BACKGROUND: The distribution of house dust mite allergen (Der p1) in living rooms with smooth floor coverings, as measured in the middle compared with the border of the floor was investigated. It was hypothesized that activity causes displacement of Der p1, from the middle towards the border. METHODS: Dust samples from the middle and border of 50 floors with smooth coverings were collected and analysed on Der p1 content in a standardized way. RESULTS: The Der p1 exposure expressed as per unit area (ng/m2) showed that border samples contained significantly more Der p1 compared with middle samples (median: 2.57 vs 0.27, respectively, P = 0.023). Presence of pets and presence of more than two inhabitants increased the difference. When expressed as per unit weight of dust (ng/g), significant differences were only detected when comparing Der p1 content of samples collected in households with three or more inhabitants [median: 2 (border) vs 53 (middle), respectively; P = 0.035]. CONCLUSIONS: The Der p1 is unequally distributed on living room floors with smooth coverings, most likely because of displacement of dust from the middle towards the border due to activity. Expression as ng/g of dust and ng/m2 could not obviously be interchangeable. 相似文献
143.
Kazunori Yoneda Tetsuya Yamamoto Eisaku Ueta Tokio Osaki 《Journal of clinical immunology》1992,12(4):289-299
Lymphokine-activated killer (LAK) cells were induced with low-dose recombinant interleukin 2 (rIL-2) and recombinant interferon- (IFN-) in 28 oral carcinoma patients. The patients received daily intravenous injections of rIL-2 (1.2×105 U/m2) and rIFN- (7.0×104 U/m2), and both natural killer (NK) and LAK activities were periodically examined. A significant increase in CD16+CD57+ and CD16+CD57– NK subsets was observed after the induction. An increase in the T-cell population was also found, with a significant increase in CD3+HLA-DR+, CD8+Leu8–, and CD4+Leu8– cells. Significant increases in NK activity, from the original level of 32.0±13.7 to 49.9±15.2%, and LAK activity, from 4.8±3.5 to 11.0±6.1%, at Day 7 were observed. Both activities were maintained at high levels during the cytokine injections, but greater enhancement of the killing activities could not be obtained subsequently. When NK and LAK activities were investigated in each subpopulation of CD3– and CD16– cells, no remarkable cytotoxic activity could be observed before induction in any subset without NK activity in CD3– cells (31.1±14.3%). At Day 7, NK activity of CD16– cells increased up to 21.4±14.9%, accompanied by an increase in CD3–-cell activity (54.5±20.6%). LAK activities of both subsets were also enhanced, with activity at Day 7 of 6.5±5.6 and 9.4±6.6% in CD16– and CD3– cells, respectively. These increased activities were maintained at the same level during the induction. Phorbol myristate acetate-induced polymorphonuclear leukocyte (PMNL) O
2
–
generation was significantly increased, from the original 81.1±28.1 to 95.6±34.9 pmol/min/104 cells, after 1 week of treatment. Protein kinase C activity in the cytosol decreased, and the activity in the membrane fraction conversely increased. No remarkable adverse effects except for mild fever were observed. Together with LAK induction ability and PMNL enhancement, with scarce toxicity, a combination of low-dose rIL-2 and rIFN- is thought to be useful in cancer treatments. 相似文献
144.
Dong Qiu Terence Cosgrove Andrew M. Howe 《Macromolecular chemistry and physics.》2005,206(22):2233-2238
Summary: The surfactant‐free synthesis of latex polymers of styrene and sodium styrenesulfonate (NaSS) was investigated. The development of size and size distribution of the particles was studied by photo‐correlation spectroscopy (PCS) and transmission electronic microscopy (TEM). The effects of NaSS concentration and the order of addition of reactants were examined in detail. The results showed that the particle size decreases with an increase in the styrene sulfonate concentration. The polydispersity index can be reduced by mixing NaSS with styrene homogeneously before adding initiator, but this leads to a slightly larger mean particle size.
145.
P. B. M. W. M. Timmermans M. J. M. C. Thoolen M. J. Mathy B. Wilffert A. de Jonge P. A. van Zwieten 《Naunyn-Schmiedeberg's archives of pharmacology》1985,329(4):404-413
Summary In pithed normotensive rats, i.v. injection of the selective
1-adrenoceptor agonist cirazolien produced vasoconstriction which was largely resistant to inhibition by nifedipine. On the other hand, the pressor effects of the selective
1-adrenoceptor agonists St 587 and Sgd 101/75 were much more effectively blocked by nifedipine, although not as effectively as the pressor effects to the selective
2-adrenoceptor agonist B-HT 920. The sensitivity to inhibition of vasoconstriction in pithed rats to the different agonists increased in the order cirazoline St 587
1-, but not to
2-adrenoceptor activation was dose-dependently enhanced. The potency of nifedipine to inhibit
1-vasoconstriction by cirazoline, St 587 and Sgd 101/75 was increased maximally to the level of efficacy at which nifedipine antagonized B-HT 920-induced vasoconstriction. The dose of phenoxybenzamine required to maximally increase the potency and efficacy of nifedipine to antagonize vasoconstriction of the
1-adrenoceptor agonists was inversely related to the level of sensitivity to blockade by nifedipine of the vasoconstriction they produced. In contrast, pretreatment of rats with the irreversible antagonist, benextramine (10 mg/kg, i.v., –100 to –60 min) did not increase the potency or efficacy of nifedipine to antagonize vasoconstriction to cirazoline, St 587, Sgd 101/75 or B-HT 920, despite irreversible blockade of
1- and
2-adrenoceptors. These data suggest that phenoxybenzamine, but not benextramine, selectively inhibits the
1-adrenoceptor mediated vasoconstrictor mechanism that is independent of influx of extracellular calcium. Moreover, the results show that the existence of receptor reserve or the number of
1-adrenoceptors activated does not determine the relative contribution of calcium influx-independent mechanisms in
1-adrenoceptor-mediated vasoconstriction.Preliminary data were communicated at the Joint Meeting of the French and German Pharmacological and Toxicological Societies, Freiburg i. Br., September 19–22, 1983 (Timmermans et al. 1983a) and at the Winter Meeting of the British Pharmacological Society, London, January 1984 (De Jonge et al. 1984) 相似文献
146.
Peter Molenaar Grant A. McPherson Errol Malta Colin Raper 《Naunyn-Schmiedeberg's archives of pharmacology》1985,331(2-3):240-246
Summary The affinity and efficacy of a number of sympathomimetic amines structurally related to prenalterol and the selective 1-adrenoceptor agonist RO 363 were determined using a combination of radioligand binding and organ bath techniques. Affinity of the molecules (pK
D) was calculated from their ability to displace the radioligand [125I]iodocyanopindolol ([125I]CYP) from -adrenoceptor sites in left atrial (1) and uterine (2) membrane homogenates. These pK
D values were used to calculate efficacy from the positive inotropic and uterine relaxant responses elicited by the drugs in organ bath experiments. The drugs studied were either arylethanolamines i.e., (–)-isoprenaline (ISO), p-hydroxyisoprenaline (pOH-ISO), compounds XIV and XVI or aryloxypropanolamine-derivatives, i.e., oxymethylene-isoprenaline (OM-ISO), prenalterol and Compound XI which possessed ap-phenol or catechol ring and an isopropyl or a homoveratryl amine substituent. Only ISO, OM-ISO, pOH-ISO and Compound XVI were active as agonists in both tissue preparations. These drugs were partial agonists which exhibited a wide range of pD2 values and did not display any marked selectivity for either -adrenoceptor subtype. Compound XI and prenalterol were inactive as agonists and together with the partial agonists behaved as competitive antagonists to ISO in the two preparations. All drugs tested displaced [125I]CYP from -adrenoceptor sites, however, there was also a wide range of potency amongst the drugs.Analysis of the structure-affinity and structure-efficacy relationships indicated that removal of the 3-hydroxyl group from the catechol ring reduces both affinity and efficacy without altering the selectivity of the drug for either -adrenoceptor subtype. While aryloxypropanolamine derivatives have generally higher affinities than arylethanol-amines, especially at -adrenoceptor sites, their efficacies are generally reduced at both -adrenoceptors. The presence of a homoveratryl group in aryloxypropanolamines enhances slightly the affinity for 1- and reduces affinity for 2-adrenoceptors. With this amine group, efficacy is markedly reduced at 2- as opposed to 2-adrenoceptor sites.Thus for prenalterol, the small degree of cardioselectivity can be attributed to the oxymethylene group whilst its lack of agonist activity (i.e., efficacy) reflects a combined action of this group and the absence of the 3-hydroxyl group on the phenyl ring. In RO363 it can be deduced that the oxymethylene group, together with the homoveratryl substituent are responsible for the observed selective affinity of the drug for 1- as opposed to 2-adrenoceptors. 相似文献
147.
V. Perhoniemi J. Salo K. Salmenkivi 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1985,366(1):339-339
Zusammenfassung 22 Patienten mit tiefer Beinvenenthrombose (DVT) und direkter operativer Ligatur der Vena cava (LIVC) wurden mit Hilfe der Strain Gauge Plethysmographie durchschnittlich 9 Jahre postoperativ nachuntersucht. Acht Patienten (36%) waren symptomfrei, ein Ulcus cruris trat bei vier Patienten (18%) auf. Patienten LIVC ohne frühere DVT wiesen keinen signifikanten Unterschied im venous reflux auf im Vergleich zu Kontrollpersonen. LIVC-Patienten mit DVT zeigten signifikante Unterschiede im venous reflux. Die Spatmorbidität dürfte eher von durchgemachten DVT als von LIVC herrühren. 相似文献
148.
E. Zanette L. Bozzao C. Buttinelli A. Mariottini S. Pappatà G. L. Lenzi 《Acta neurochirurgica》1987,89(1-2):43-47
Summary Tumour growth essentially requires fibrin formation and fibrinopeptide A (FPA) is liberated into the circulation on fibrin formation. In the present study, a possible elevation of serum FPA level was examined in patients with metastatic brain tumour. A significant elevation of serum FPA level was shown in all 6 patients with metastatic brain tumour, when blood was drawn from the internal jugular vein. It was extremely high in 2 patients with rapidly growing tumour. However, such a significant elevation was not shown in 3 cancer patients without brain metastasis or in 1 patient with a huge meningioma. This suggests the possibility that the presence of metastatic brain tumour could be detected by measuring FPA in blood drawn form the internal jugular vein. This also suggests the tendency that elevation of serum FPA is higher in patients with more rapidly growing tumour.Infusion of urokinase into the internal carotid artery resulted in an elevation of serum fibrinopeptide B (1)15–42 (FPB) in 5 patients with metastatic brain tumour, when blood was drawn from the internal jugular vein. This suggests that urokinase could induce fibrinolysis in the tumour tissue, though this remains in conclusive because of the lack of complete controls. 相似文献
149.
79. Totalprothese der Hüfte: Das Verfahren mit Verwendung von Zement — Indikation,Technik, Resultate
R. Schneider 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1987,372(1):457-464
Zusammenfassung Die Prothese mu\ dem Knochen angepät werden. Keine motorische Bearbeitung. Biomechanisch notwendig ist eine möglichst grosse Kontaktzone ohne Relativbewegungen. Eine mägenaue Prothese lässt sich nicht einführen. Massgenauigkeit ist nur mit Zement realisierbar. Sein Nachteil der zu grossen Elastizität bei dickerer Schicht muss durch ein möglichst voluminöses, in der Markhöhle verkeiltes Metallimplantat kompensiert werden. Osteosyntheseplatten neben dem Schaft ergeben im Zementverbund eine Art Individualprothese. Der Zement ist langfristig biokompatibel. Wichtig ist eine korrekte Zementiertechnik. 95% erfolgreiche Resultate bei 373 Ersatzoperationen von 1977–1985 beweisen die Gültigkeit der biomechanischen Überlegungen, da gleiches Implantationsmaterial verwendet wurde. Allergie als Lokkerungsfaktor fült praktisch ausser Betracht. In Knochendefekte gehërt Knochen, nicht Zement. 相似文献
150.
P. Bauer H. Stützer A. Vierzig 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1987,372(1):603-606
Zusammenfassung Es wird auf die Problematik von Aussagen über Radikalität der Operation und Prognose beim Magencarcinom aus retrospektiven oder prospektiven Beobachtungsstudien hingewiesen. Einige Gründe für sich widersprechende oder nicht reproduzierbare Resultate in Subgruppen werden aufgezeigt. Insbesondere wird auf das Problem der Suche nach signifikanten Ergebnissen durch multiple Testanwendungen in den verschiedensten Subgruppen aufmerksam gemacht. Bei offenen Fragen erscheinen nach den Kriterien des statistischen Schliessens randomisierte Studien angebracht. 相似文献