全文获取类型
收费全文 | 17585篇 |
免费 | 1126篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 579篇 |
儿科学 | 1481篇 |
妇产科学 | 600篇 |
基础医学 | 1199篇 |
口腔科学 | 1249篇 |
临床医学 | 1409篇 |
内科学 | 3060篇 |
皮肤病学 | 453篇 |
神经病学 | 1171篇 |
特种医学 | 798篇 |
外科学 | 4050篇 |
综合类 | 99篇 |
一般理论 | 8篇 |
预防医学 | 553篇 |
眼科学 | 551篇 |
药学 | 935篇 |
中国医学 | 47篇 |
肿瘤学 | 483篇 |
出版年
2024年 | 15篇 |
2023年 | 247篇 |
2022年 | 132篇 |
2021年 | 336篇 |
2020年 | 296篇 |
2019年 | 351篇 |
2018年 | 712篇 |
2017年 | 594篇 |
2016年 | 727篇 |
2015年 | 609篇 |
2014年 | 772篇 |
2013年 | 1321篇 |
2012年 | 1009篇 |
2011年 | 1109篇 |
2010年 | 805篇 |
2009年 | 453篇 |
2008年 | 877篇 |
2007年 | 869篇 |
2006年 | 1005篇 |
2005年 | 922篇 |
2004年 | 900篇 |
2003年 | 819篇 |
2002年 | 845篇 |
2001年 | 548篇 |
2000年 | 580篇 |
1999年 | 415篇 |
1998年 | 197篇 |
1997年 | 162篇 |
1996年 | 175篇 |
1995年 | 103篇 |
1994年 | 112篇 |
1993年 | 88篇 |
1992年 | 61篇 |
1991年 | 62篇 |
1990年 | 48篇 |
1989年 | 31篇 |
1988年 | 34篇 |
1987年 | 18篇 |
1986年 | 24篇 |
1985年 | 21篇 |
1984年 | 29篇 |
1983年 | 23篇 |
1982年 | 27篇 |
1981年 | 28篇 |
1980年 | 23篇 |
1979年 | 19篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
A. Tümer N. Öztürk-Demir C. Basar-Eroglu A. Noyan 《Journal of muscle research and cell motility》1983,4(1):103-113
Summary In this study the spontaneous activities of prescapular lymph nodes, which were isolated from calves, goats and sheep and mesenteric lymph nodes of guinea-pigs were recorded and analysed in the frequency domain. Stretch-evoked contractions of the mesenteric lymph nodes were also recorded and their frequency characteristics analysed.The preparations were placed in a Krebs solution which was kept at 37° C and bubbled continuously with a mixture of 95% O2 and 5% CO2. The tension changes occurring in the lymph nodes were recorded. The patterns obtained were initially transformed into numerical values which were then used to obtain autocorrelation functions and power spectra, according to the time series analysis method. A passive stretch of 100 s duration was applied to the mesenteric lymph nodes and the responses were examined using the transient response-frequency characteristics method.It was observed that prescapular and mesenteric lymph nodes had spontaneous activities due to the contractions of the smooth muscles within the nodes. A frequency analysis of these contractions indicated that at least three contractile components were responsible for the contractions; these components contract within the frequency bands of 0.01–0.04 Hz, 0.05–0.07 Hz and 0.09–0.14 Hz respectively. It was also observed that the spontaneous activities could be regulated and synchronized by stretch. It is suggested that these contractions of the lymph nodes play an essential role in lymph propulsion within the nodes. 相似文献
92.
Comparison of three methods for detection of pneumococcal antigen in sputum of patients with community-acquired pneumonia 总被引:5,自引:0,他引:5
A. Örtqvist I. Jönsson M. Kalin A. Krook 《European journal of clinical microbiology & infectious diseases》1989,8(11):956-961
In a prospective study of 249 patients with community-acquired pneumonia, three tests for the detection of pneumococcal antigen in sputum were compared: a coagglutination test for detecting capsular antigens (Cap-CoA), a sandwich enzyme immunoassay (PnC-EIA) and a coagglutination test (PnC-CoA), both the latter detecting the pneumococcal C-polysaccharide common to all pneumococcal types. Sixty-three patients had culture-positive pneumococcal pneumonia, 45 pneumonia caused by other bacteria and 141 pneumonia of viral or unknown etiology. The sensitivity of Cap-CoA (63%) and PnC-CoA (65%) was somewhat higher than that of PnC-EIA (49%), but not significantly so. The specificity was 96–98% for all three methods. Using PnC-CoA 66 patients with possible pneumococcal infection were detected, the diagnosis being verified by culture in 41. Using Cap-CoA 59 such patients were detected, the diagnosis being verified in 40, and using the PnC-EIA 47 such patients were detected, the diagnosis being verified in 31. Antigen was found almost as often in non-purulent as in purulent samples, and as often in washed as in non-washed purulent samples. However, antibiotic treatment before the sputum sample was obtained resulted in significantly lower sensitivity of both PnC-CoA and Cap-CoA. This study confirms the high sensitivity and specificity of methods for pneumococcal antigen detection in sputum. Since CoA is easier and quicker to perform, and cheaper than the EIA, either PnC-CoA or Cap-CoA would seem to be the technique of choice for detection of pneumococcal antigen, whereby all sputum samples, including non-purulent samples, can be used. 相似文献
93.
Yusuf E. Karakullukçu Tayfun Özçelik Nuran Gökhan 《Pflügers Archiv : European journal of physiology》1987,410(6):657-663
Reperfusion of hearts with a Ca2+-containing medium after a perfusion period in Ca2+-free medium results in irreversible cell damage (calcium paradox). In this investigation we have studied coronary flow and cyclic AMP and cyclic GMP levels after several periods of Ca2+-free perfusion in isolated rat hearts. We also investigated the effects of papaverine (Pap), noradrenaline (NA), acetylcholine (ACh) and absence of inorganic phosphate during Ca2+-free perfusion on coronary flow (CF) and cyclic nucleotide levels. Inability of the heart to recover contractile activity with development of contracture during the reperfusion period was accepted as indicative of the calcium paradox. Ca2+-free perfusion alone and NA and absence of inorganic phosphate during the Ca2+-free perfusion period increased CF, whereas Pap and ACh decreased it. However, only Ca2+-free perfusion and NA elevated cyclic AMP. On the other hand, Pap and ACh increased cyclic GMP (with a transient rise of cyclic AMP in Pap infusion), and absence of inorganic phosphate decreased both cyclic AMP and cyclic GMP. Pap, ACh and absence of phosphate prevented the calcium paradox. Our study suggests that increased cyclic AMP during the Ca2+-free perfusion may contribute, with the other factors, to the occurrence of the calcium paradox. 相似文献
94.
A. Öhlen L. Liudbom W. Staines T. Hökfelt A.C. Cuello J.A. Fischer P. Hedgvist 《Naunyn-Schmiedeberg's archives of pharmacology》1987,336(1):87-93
Summary 1. The distribution and microvascular effects of substance P (SP) and calcitonin gene-related peptide (CGRP) were studied in the rabbit tenuissimus muscle using immunohistochemistry and intravital microscopy. 2. Individual fibers within nerve bundles and along blood vessels in the muscle were found to be immunoreactive (IR) for both SP and CGRP, thus showing an apparently complete coexistence for these peptides. In dorsal root ganglia most SP-positive cells were also CGRP-IR, but the latter cells were somewhat more numerous than SP-IR cells. 3. When applied topically to the muscle, both SP and CGRP increased blood flow in a dose-dependent manner, but CGRP was more potent and caused responses of longer duration. Both SP and CGRP dilated transverse arterioles, but they had little or no effect on the smaller terminal arterioles. This resulted in a redistribution of blood flow to the connective tissue adjacent to the muscle. 4. SP, but not CGRP, elicited vigorous vasomotion in larger arterioles and caused the formation of aggregates of platelets and leukocytes in the venules. Neither flow increase, nor vasomotion or aggregate formation were influenced by pretreatment of the animals with mepyramine, cimetidine or indomethacin. Capsaicin (1 M) had a powerful effect on transverse arterioles resembling that of both SP and CGRP. 5. It is concluded that some of the vascular effects hitherto ascribed to SP on the basis of nerve stimulation and application of capsaicin might, at least in part, be due to release of CGRP.
Send offprint requests to: A. Ohlen, Department of Physiology, Karolinska Institutet, S-104 01 Stockholm, Sweden 相似文献
95.
The dose-dependent effect of acute zimeldine and alaproclate treatment upon the acquisition of two-way and one-way active avoidance in the rat was studied in a single-session and in a repeated-sessions design. Zimeldine (5–20 mg/kg, IP), but not alaproclate, caused disruptions of two-way avoidance acquisition. Acquisition deficits were also caused by citalopram and fluoxetine but not the other antidepressant drugs tested. Zimeldine, but not alaproclate or desipramine, caused a slight but non-significant impairment of one-way active avoidance; neither zimeldine nor alaproclate produced any effects upon fear conditioning and retention testing. The long-term action of p-chloroamphetamine (2×10 mg/kg) antagonised the acute zimeldine effect totally, and chronic treatment with zimeldine (15 days, 1×50 mol/kg) and chlorimipramine (15 days, 2×10 mol/kg) also caused some partial blockade of the two-way avoidance deficit. These data seem to suggest some involvement of serotonin (5-HT) in the observed disruptions of two-way active avoidance caused by acute zimeldine treatment. 相似文献
96.
Özışık Pınar Akdemir Özdener Kubilay Murat Ural Berkan Er Uygur Savaş Ali 《Zeitschrift fur Gesundheitswissenschaften》2022,30(6):1431-1440
Journal of Public Health - Because an increasing number of patients travel internationally to seek medical care, Turkey offers comprehensive and outstanding services under extraordinary conditions... 相似文献
97.
Wahidie Diana Yılmaz-Aslan Yüce Ölcer Sabahat Aksakal Tuğba Brzoska Patrick 《Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz》2021,64(5):616-624
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - Um die Ausbreitung von SARS-CoV‑2 (schweres akutes Atemwegssyndrom-Coronavirus-Typ 2) zu verlangsamen, haben Bund... 相似文献
98.
99.
Helvacı Özant Korucu Berfu Gonul Ipek İsik Arınsoy Turgay Guz Galip Derici Ulver 《International urology and nephrology》2021,53(1):105-109
International Urology and Nephrology - The number of kidney biopsies (KB) performed in elderly patients has been increasing. Safety and usefulness of elderly KB have been well established, whereas... 相似文献
100.
Asiye İzem Sandal Hatice Şenlikci Merve Yılmazer Burcu Kartal Bedia Palabıyık Özen Banu Özdaş 《Andrologia》2021,53(5):e14032
The aim of the study was to investigate the efficiency of ram seminal plasma and fetal calf serum on freezing of buck semen. Twenty ejaculates were collected using an electro-ejaculator and split into six groups. While FCS additive was not used in A1, A2 and A3 groups, 10% FCS was added to B1, B2 and B3 groups. These groups were then edited according to whether the buck or ram SP was involved. The design of the groups was done as follows: Group A1 (control 1), group A2 without buck SP, group A3 containing ram SP instead of buck SP. Groups B1 (control 2), B2 and B3 were the FCS added forms of these groups. Progressive sperm motility percentages in Group A1 and Group B2 were found to be higher when compared to the lowest Group B3. There were no significant differences between the groups in neither the levels of reactive oxygen species nor the enzyme and glutathione activities. In conclusion, the lack of statistical difference between the groups suggested that despite the supplements used but only when the buck spermatozoa structure was healthy, the cell could preserve acrosome, DNA and the integrity of membrane. 相似文献