首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   94806篇
  免费   8996篇
  国内免费   187篇
耳鼻咽喉   1291篇
儿科学   2970篇
妇产科学   1981篇
基础医学   13358篇
口腔科学   2137篇
临床医学   11469篇
内科学   16976篇
皮肤病学   1484篇
神经病学   7853篇
特种医学   3094篇
外国民族医学   12篇
外科学   13088篇
综合类   1824篇
一般理论   77篇
预防医学   10492篇
眼科学   2366篇
药学   7726篇
  1篇
中国医学   101篇
肿瘤学   5689篇
  2021年   1400篇
  2020年   903篇
  2019年   1362篇
  2018年   1683篇
  2017年   1256篇
  2016年   1333篇
  2015年   1558篇
  2014年   2022篇
  2013年   3156篇
  2012年   4397篇
  2011年   4666篇
  2010年   2490篇
  2009年   2338篇
  2008年   3956篇
  2007年   4355篇
  2006年   4184篇
  2005年   4252篇
  2004年   3942篇
  2003年   3672篇
  2002年   3548篇
  2001年   2859篇
  2000年   2954篇
  1999年   2634篇
  1998年   1217篇
  1997年   989篇
  1996年   940篇
  1995年   868篇
  1994年   908篇
  1993年   801篇
  1992年   2189篇
  1991年   2098篇
  1990年   1958篇
  1989年   1932篇
  1988年   1831篇
  1987年   1815篇
  1986年   1732篇
  1985年   1719篇
  1984年   1438篇
  1983年   1305篇
  1982年   901篇
  1981年   767篇
  1980年   678篇
  1979年   1266篇
  1978年   915篇
  1977年   791篇
  1976年   739篇
  1975年   730篇
  1974年   883篇
  1973年   780篇
  1972年   760篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Changes in semen parameters are presented for 4708 patients treated for infertility. The largest group comprised patients with oligoasthenozoospermia of various grades (57.7%). Improvement in the seminal state was noted in 70.3%. The percentage of achieved normospermia increased proportionally to the initial semen state. Pregnancy rate also increased proportionally to the initial seminal state. Among the patients' wives 20.4% conceived: 28.2% of these pregnancies had occurred after having achieved normospermia, while in 71.8% the seminal states were still below the accepted normal values.  相似文献   
42.
Ten patients with rheumatoid arthritis (RA) were evaluated in a placebo-controlled, double-blind study examining the clinical efficacy of a novel nonsteroidal anti-inflammatory agent: Tenidap (CP-66,248). RA patients receiving active drug therapy (n = 6) demonstrated clinically significant improvements in observer assessment of pain (p less than 0.025), painful joint count (p less than 0.010), and overall clinical assessment as based on a modified rheumatoid activity index, MRAI (p less than 0.025). In parallel laboratory assays, Tenidap was found to exhibit a significant in vitro dose-dependent inhibition of ionophore-stimulated neutrophil production of the 5-lipoxygenase product: [3H]leukotriene B4 (LTB4). Although more importantly, Tenidap was also found to exhibit an in vitro dose-dependent inhibition (IC50 20 microM) of the ionophore-stimulated release (deacylation) of the precursor [3H]arachidonic acid (AA) from membrane phospholipids. In further studies, Tenidap did not have any effect on fMLP-induced neutrophil chemotactic response. These results suggest that one of the possible mechanisms for the clinical effectiveness of this agent, may be through its effect at inhibiting the release of free AA from membrane phospholipids and therefore limiting its further metabolism into certain biologically-active inflammatory lipids.  相似文献   
43.
44.
The talar beak is a well-described secondary sign of talocalcaneal coalition but is not pathognomonic of the condition and may be seen in other causes of restricted or abnormal subtalar motion. We present an unusual complication of talar beaks in two patients who sustained fractures through their beaks. One of the patients described did not have a talocalcaneal coalition but had developed a beak following a compound fracture dislocation of the ankle joint complicated by infection, a previously undescribed predisposing cause.  相似文献   
45.
Cobb's collar or Moormann's ring is a stricture of the bulbar urethra which is largely unrecognised but has considerable relevance urologically as the site of congenital or post-instrumental strictures. The history, anatomy, embryology and surgical importance are reported.  相似文献   
46.
The yellow color of atherosclerotic plaque is due to the presence of carotenoids, which absorb light between 430–530 nm and account for the preferential ablation of plaque by the pulsed dye laser operating at 480 nm. This study was designed to examine tissue uptake of β-carotene and the effect of uptake on arterial plaque ablation. Forty-two atherosclerotic NZW rabbits were given intravenous β-carotene at a dose of 40 mg/kg, twice weekly and killed between 1 hour and 28 days after the initial injection. β-carotene was not detected in control specimens but was significantly greater in plaque than in normal wall at all time points following β-carotene injection (P < 0.04 Mann Whitney U test). The ablation threshold was significantly lower in β-carotene treated plaque than in untreated plaque or normal arterial wall (P < 0.01, Fisher's exact test). In this model β-carotene is preferentially taken up into arterial plaque, resulting in increased absorption of laser radiation at 480 nm and enhanced tissue ablation. © 1993 Wiley-Liss, Inc.  相似文献   
47.
Cellular toxicity and cellular carcinogenesis are closely linked. In the kidney, this relationship has been emphasized by the recent discovery of a number of putatively non-mutagenic chemicals that result in acute and chronic toxicity and ultimately in carcinogenesis, especially in the male rat. Many, but not all such compounds, result in renal PTE phagolysosomal overload. At the same time, known metabolites of other carcinogens, e.g., HCBD and FBPA, result in acute renal injury and/or necrosis, followed by chronic tubular disease, interstitial nephritis, and ultimately carcinogenesis. A series of cell mechanisms have been suggested that lead from acute cell injury to altered control of cell division. These mechanisms appear to involve ion deregulation, (especially [Ca2+]i) resulting from a variety of continued injuries, (e.g., oxidative stress from inflammatory cells) and ultimately leading to altered gene expression.  相似文献   
48.
49.
It is well established that the circadian clock of the suprachiasmatic nuclei (SCN) is entrained by light. More recently, the potent effects of arousing, non-photic cues on the clock have been recognized. The neural mediators of non-photic entrainment are yet to be identified. To examine the contribution of the thalamic intergeniculate leaflet (IGL) and its NPY-immunopositive projection, the geniculo-hypothalamic tract to non-photic entrainment by arousal, male Syrian hamsters received lesions of the IGL (IGLX) which ablated NPY-immunoreactivity in the SCN. Their circadian responses to both photic and non-photic cues were then tested. Lesions resulted in a delay in the timing of activity onset following lights out, but had no effect on the behavioural or cellular circadian responses to phase-advancing light pulses presented at circadian time (CT) CT19 (where CT12 represents the time of activity onset). Injection with a benzodiazepine (chlordiazepoxide, 100 mg/kg) at CT6 suppressed wheel-running, increased general locomotion of intact controls and induced large phase advances of the circadian rhythm of wheel-running. Chlordiazepoxide also inhibited wheel-running in lesioned animals, but there was no significant increase in general locomotion and the lesioned animals did not phase advance. Serial arousal by injection of saline at intervals of 23.5 h for 6 days entrained the circadian rhythm of wheel-running of intact hamsters and was associated with an increase in general locomotor activity. Entrainment by serial arousal was abolished by IGLX. However, the lesioned animals did show a clear behavioural response to every presentation of the non-photic cue. These results show that the IGL is a necessary component of the neural pathways mediating both arousal- and benzodiazepine-induced non-photic entrainment.  相似文献   
50.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号