全文获取类型
收费全文 | 352974篇 |
免费 | 15222篇 |
国内免费 | 1048篇 |
专业分类
耳鼻咽喉 | 4506篇 |
儿科学 | 11324篇 |
妇产科学 | 8424篇 |
基础医学 | 46066篇 |
口腔科学 | 9249篇 |
临床医学 | 30638篇 |
内科学 | 68269篇 |
皮肤病学 | 7818篇 |
神经病学 | 26190篇 |
特种医学 | 17468篇 |
外国民族医学 | 111篇 |
外科学 | 54364篇 |
综合类 | 3046篇 |
一般理论 | 110篇 |
预防医学 | 28929篇 |
眼科学 | 7648篇 |
药学 | 23641篇 |
2篇 | |
中国医学 | 381篇 |
肿瘤学 | 21060篇 |
出版年
2021年 | 3537篇 |
2020年 | 2235篇 |
2019年 | 3221篇 |
2018年 | 6969篇 |
2017年 | 6547篇 |
2016年 | 6233篇 |
2015年 | 8277篇 |
2014年 | 9222篇 |
2013年 | 10124篇 |
2012年 | 19876篇 |
2011年 | 15668篇 |
2010年 | 8441篇 |
2009年 | 9801篇 |
2008年 | 11834篇 |
2007年 | 12957篇 |
2006年 | 13090篇 |
2005年 | 20985篇 |
2004年 | 21633篇 |
2003年 | 16701篇 |
2002年 | 11673篇 |
2001年 | 6515篇 |
2000年 | 3611篇 |
1999年 | 8005篇 |
1998年 | 2468篇 |
1997年 | 1852篇 |
1992年 | 8342篇 |
1991年 | 8458篇 |
1990年 | 8487篇 |
1989年 | 7956篇 |
1988年 | 7416篇 |
1987年 | 7171篇 |
1986年 | 6885篇 |
1985年 | 6142篇 |
1984年 | 4543篇 |
1983年 | 3732篇 |
1982年 | 1979篇 |
1979年 | 4508篇 |
1978年 | 3032篇 |
1977年 | 2338篇 |
1976年 | 2087篇 |
1975年 | 2926篇 |
1974年 | 3635篇 |
1973年 | 3212篇 |
1972年 | 3171篇 |
1971年 | 3062篇 |
1970年 | 2858篇 |
1969年 | 2720篇 |
1968年 | 2484篇 |
1967年 | 2361篇 |
1966年 | 2100篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Klaus-Dietmar Merboldt Harald Bruhn Wolfgang Hanicke Thomas Michaelis Jens Frahm 《Magnetic resonance in medicine》1992,25(1):187-194
Localized proton NMR spectroscopy was used to study cerebral metabolism in the visual cortex of healthy adults during rest and photic stimulation. Basal lactate levels showed considerable interindividual differences ranging from below detectability (less than 0.3 mM) to about 1 mM without consistent alteration during photic stimulation. Local brain glucose levels were significantly reduced (approximately 50%) during the entire period of photic stimulation and recovered to resting levels (approximately 0.8 mM) within 10 min after the end of stimulation. This decrease reflects the establishment of a new equilibrium due to enhanced delivery (blood flow) and enhanced consumption. The absence of lactate accumulation supports the hypothesis of a rapid efflux of lactate from brain tissue under activated conditions. 相似文献
992.
Anal sphincter size measured by endosonography in healthy volunteers. Effect of age, sex, and parity. 总被引:8,自引:0,他引:8
M B Nielsen C Hauge O O Rasmussen M S?rensen J F Pedersen J Christiansen 《Acta radiologica (Stockholm, Sweden : 1987)》1992,33(5):453-456
The anal sphincter muscles consist of the circular internal and external sphincters together with the sling-shaped associated puborectalis muscle. Ten men, 10 women with no vaginal deliveries, and 10 women with one or more vaginal deliveries were studied with anal endosonography using a 7 MHz multiplanar endoprobe. The thickness of the internal sphincter and the thickness, length, and cross-sectional area of the external sphincter were measured and related to age, sex, and parity. Reproducibility was assessed by similar measurements on different days in 10 volunteers. Anal sphincter size was the same in men and women and was not affected by the number of child births. Internal sphincter muscle thickness increased with age. Anal manometry and electromyography with an anal sponge were performed in all volunteers but the results did not correlate to any of the anal sphincter dimensions. Our conclusion is that although there are some limitations, endosonography can be used to determine the size of the anal sphincter muscles. 相似文献
993.
M A Brancós P Peris J M Miró A Monegal J M Gatell J Mallolas J Mensa S García J Mu?oz-Gomez 《Seminars in arthritis and rheumatism》1991,21(2):81-87
Over a 6-year period (1982 to 1988), 36 episodes of septic arthritis were diagnosed in 35 heroin addicts from Barcelona, Spain. Thirty (86%) were men and five (14%) were women, with a mean age of 24 years (range, 14 to 39). Twenty-nine episodes (80%) were monoarticular and seven (20%) were oligoarticular. The sacroiliac (16 cases), sternoclavicular (8), hip (5), and shoulder (4) joints were most frequently infected. Staphylococcus aureus and Pseudomonas aeruginosa were the etiological agents in 75% and 11% of episodes, respectively. Response to antibiotic treatment was good in 32 cases (90%), eight patients needed surgical drainage, and none died. We conclude that septic arthritis in heroin addicts localizes predominantly in axial joints. In our geographic area, infection with S aureus is more frequent than with gram-negative rods such as P aeruginosa or Serratia marcescens, which are most frequently found in reports from the United States. 相似文献
994.
S Rydén M Fern? T M?ller K Aspegren L Bergljung D Killander T Landberg 《Acta oncologica (Stockholm, Sweden)》1992,31(2):271-274
In a multicenter trial of adjuvant therapy in stage II breast cancer, 719 postmenopausal patients were randomized to one of three treatment regimens: radiotherapy only or in combination with adjuvant tamoxifen for one year, or adjuvant tamoxifen without radiotherapy. At twelve years of follow-up (median 9 years), no statistically significant differences in survival or recurrence-free survival were observed. However, the rate of loco-regional recurrency was lower among patients treated with both radiotherapy and tamoxifen. The rate of bilateral breast cancer was reduced in tamoxifen-treated patients whereas the rate of new primary malignancies other than breast cancer was somewhat higher in tamoxifen-treated patients. Adjuvant therapy in breast cancer may influence not only breast cancer recurrences and mortality but also later disease patterns and cause-specific mortality. 相似文献
995.
T J Whelan A J Dembo R S Bush J F Sturgeon S Fine J F Pringle G A Rawlings G M Thomas J Simm 《International journal of radiation oncology, biology, physics》1992,22(5):853-858
We examined the records of 105 patients with advanced ovarian cancer who had been treated with cisplatin combination chemotherapy followed by abdominopelvic radiotherapy. The purpose was to define the morbidity of this approach, and identify those factors predictive of toxicity. Acute toxicity resulting in delay or failure to complete treatment was most commonly due to myelosuppression. Nine of 105 patients (8.6%) required surgery for bowel obstruction that was not due to recurrent disease, 3 had an episode of bowel obstruction that settled conservatively, and a further 5 underwent surgery for obstruction due to recurrent tumor. The presence of both a dose of abdominopelvic radiotherapy over 2250 cGy, as well as a second-look laparotomy prior to radiotherapy, was associated with an increased risk of serious bowel complications. The increased frequency of late bowel morbidity seen in the combined modality group is likely explained by the presence of these two factors, rather than the exposure to chemotherapeutic agents per se. These observations are supported by the published literature. 相似文献
996.
Regional differences in endothelin converting enzyme activity in rat brain: inhibition by phosphoramidon and EDTA.
下载免费PDF全文
![点击此处可从《British journal of pharmacology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
T. D. Warner G. P. Budzik T. Matsumoto J. A. Mitchell U. F?rstermann F. Murad 《British journal of pharmacology》1992,106(4):948-952
1. It has been demonstrated previously that conversion of big endothelin-1 (bET-1) to endothelin-1 (ET-1) is inhibited in vitro and in vivo by phosphoramidon. In addition, ET-1 binding sites and mRNA have been shown within the brain. Here we expand upon our previous observation that rat brain contains phosphoramidon-inhibitable endothelin converting enzyme (ECE) and show that this activity is not uniformly distributed throughout the brain. 2. ECE activity was detected by a bioassay which depended upon the 10,000 fold difference in potency between bET-1 and ET-1 as stimulants of guanosine 3':5'-cyclic monophosphate (cyclic GMP) accumulation in kidney epithelial (PK1) cells of the pig. Data were confirmed by specific enzyme-linked immunosorbent assay (ELISA) employing antibody directed against ET-1/3(17-21). 3. Following homogenization of the whole brain and ultracentrifugation the 100,000 g pellet contained greater than 4 times more ECE activity than the cytosol. Washing of the pellet with KCl (1 M) and extraction with the detergent CHAPS (20 mM) revealed a phosphoramidon-inhibitable ECE within the residual particulate fraction (nominally classified as the cytoskeletal fraction). Phosphoramidon (IC50, approx. 5 microM) or EDTA inhibited the conversion of bET-1 to ET-1 by the cytoskeletal fraction of rat brain by more than 60%.2+ 4. Following dissection of rat brain into olfactory bulb, cerebral cortex, striatum, hippocampus, cerebellum, midbrain (including thalamus), hypothalamus and medulla oblongata (including pons) the greatest ECE was detected in the hypothalamus and medulla oblongata.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
997.
B Lagerqvist C Sylvén E Theodorsen L Kaijser G Helmius A Waldenstr?m 《Cardiovascular research》1992,26(8):810-814
OBJECTIVE: Adenosine may induce chest pain in at least two ways, either by direct stimulation of sensory afferents before actual ischaemia occurs or secondary to ischaemia. The aim was to study if the mechanism of pain induction may depend on the method of adenosine administration. METHODS: Increasing doses of adenosine were given to seven male patients with ischaemic heart disease referred for coronary angiography: first as a bolus intracoronary injection (2.5-50 mumol), second as a 1 ml.min-1 steady state infusion (0.01-20 mumol.min-1) and third as an intravenous steady state infusion (0.076-0.76 mumol.kg-1 x min-1). Pain, rate-pressure product, coronary sinus blood flow, and ECG were monitored. Lactate was analysed in coronary sinus and arterial blood. RESULTS: After intracoronary bolus injection there were no signs of myocardial ischaemia, whereas during intracoronary steady state infusion, and in spite of a lower, but definite, degree of pain, 5/7 patients showed myocardial lactate production and three patients showed ST depression. During the intravenous steady state infusion 6/6 patients showed ST depression. CONCLUSIONS: These findings suggest that when using adenosine for studies on the mechanisms of chest pain in patients with ischaemic heart disease it is preferable to use an intracoronary bolus injection technique rather than a steady state infusion, as the risk of inducing ischaemia with the latter model cannot be ignored. 相似文献
998.
Glutathione S-transferases in human testicular germ cell tumors: changes of expression and activity.
Glutathione S-transferases are involved in the detoxification of carcinogens and xenobiotics and are potentially associated with the development of drug-resistance. Forty-six testicular germ cell tumors and 33 adjacent normal testicular tissue specimens were analyzed at the RNA level for the expression of glutathione S-transferase alpha and pi. Glutathione S-transferase alpha was expressed in 31 of the 33 normal testicular tissues (94%) but in only three of the 46 germ cell tumors (7%). Glutathione S-transferase pi mRNA was detected in all normal and malignant testicular tissue samples. Thirteen testicular germ cell tumors and eight normal testicular tissue samples were analyzed at the protein level. The mean specific activity of total cytosolic glutathione S-transferase in tumor tissue was decreased by about 80% as compared to normal testicular tissue. Protein analysis of the glutathione S-transferase subunits of normal testicular tissue demonstrated the presence of the glutathione S-transferase classes alpha, mu and pi, with a predominance of the mu class. In testicular germ cell tumors the glutathione S-transferase subunit pattern showed a predominance of glutathione S-transferase pi representing 88% +/- 3% of total glutathione S-transferase. Since all three glutathione S-transferase isoenzyme classes contribute to the resistance to antineoplastic drugs, the altered glutathione S-transferase isoenzyme pattern and the decrease of glutathione S-transferase activity may play a role in the high inherent drug sensitivity of human testicular germ cell tumors. 相似文献
999.
1000.
S. Haug C. Schnopp J. Ring R. F?lster-Holst D. Abeck 《Der Hautarzt; Zeitschrift für Dermatologie, Venerologie, und verwandte Gebiete》2002,174(3):683-685
Es wird über 4 Kleinkinder berichtet, bei denen ein Gianotti-Crosti-Syndrom (GCS) mit einer Latenz von 6–8 Tagen nach Impfung
auftrat. Nachfolgende Auffrischungsimpfungen wurden problemlos vertragen. W?hrend das Auftreten eines GCS in Assoziation mit
einer Virusinfektion gut dokumentiert ist, liegen über das Auftreten eines GCS im Anschluss an eine Impfung nur wenige Mitteilungen
vor. Auf einen derartig m?glichen Zusammenhang sollte jedoch bei Vorstellung dieses Krankheitsbildes (GCS) im Rahmen der Anamneseerhebung
unbedingt eingegangen werden. 相似文献