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   1476篇
  免费   99篇
  国内免费   20篇
耳鼻咽喉   7篇
儿科学   47篇
妇产科学   20篇
基础医学   147篇
口腔科学   55篇
临床医学   212篇
内科学   324篇
皮肤病学   7篇
神经病学   78篇
特种医学   179篇
外科学   150篇
综合类   32篇
预防医学   115篇
眼科学   14篇
药学   129篇
肿瘤学   79篇
  2023年   16篇
  2022年   15篇
  2021年   34篇
  2020年   18篇
  2019年   23篇
  2018年   24篇
  2017年   17篇
  2016年   25篇
  2015年   17篇
  2014年   29篇
  2013年   46篇
  2012年   46篇
  2011年   47篇
  2010年   38篇
  2009年   59篇
  2008年   68篇
  2007年   70篇
  2006年   46篇
  2005年   49篇
  2004年   40篇
  2003年   52篇
  2002年   48篇
  2001年   44篇
  2000年   41篇
  1999年   31篇
  1998年   50篇
  1997年   43篇
  1996年   53篇
  1995年   40篇
  1994年   32篇
  1993年   33篇
  1992年   21篇
  1991年   17篇
  1990年   16篇
  1989年   37篇
  1988年   41篇
  1987年   27篇
  1986年   19篇
  1985年   31篇
  1984年   21篇
  1983年   16篇
  1982年   24篇
  1981年   13篇
  1980年   18篇
  1979年   12篇
  1978年   16篇
  1977年   14篇
  1976年   11篇
  1973年   8篇
  1972年   10篇
排序方式: 共有1595条查询结果,搜索用时 31 毫秒
101.
PURPOSE: A retrospective study was conducted at three centers to examine the participation of neutrophils and eosinophils in the inflammatory processes associated with atopic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC). METHODS: Conjunctival specimens were obtained from four patients with AKC, six with VKC, and five normal subjects. Indirect immunofluorescent staining was used to localize neutrophil elastase (NE) and eosinophil granule major basic protein (MBP) in serial sections of all specimens. RESULTS: Specimens from both AKC and VKC patients revealed extracellular deposition of NE and MBP. Control specimens showed no or minimal extracellular NE, and no MBP. Statistical analysis demonstrated significantly greater extracellular MBP deposition in AKC specimens compared to controls (p = 0.009), and VKC specimens showed significantly greater staining for both extracellular MBP (p = 0.005) and NE (p = 0.006). CONCLUSIONS: These results suggest that neutrophils, in addition to eosinophils, play an active role in the pathogenesis of AKC and VKC as evidenced by the extracellular deposition of their specific granule proteins.  相似文献   
102.
103.
The effect of diazepam on methadone self-administration was examined. Five methadone-maintained patients with a history of benzodiazepine abuse were recruited. Patients were stabilized on 80 mg of methadone per day. After stabilization patients participated in methadone self-administration sessions. During each session, 128 presses (fixed ratio 128) of 1 button delivered 10 ml of 0.054 mg/ml methadone solution. The same number of button presses on a 2nd button delivered 10 ml of vehicle. Forty-five min prior to the self-administration session, 0 (placebo), 5, 10, or 20 mg per 70 kg body weight diazepam was administered. Ratings of drug liking, goodness, strength, and high were collected 5, 30, 60, 90, and 150 min after the end of the self-administration session. Diazepam pretreatment significantly decreased the amount of methadone consumed. The 10- and 20-mg diazepam doses significantly increased reports of good, like, strong, and high.  相似文献   
104.
RATIONALE: Polydrug abuse is a problem that has been infrequently examined. In the present study, drug self-administration procedures were used to investigate the reinforcing effects of drug combinations. OBJECTIVES: To determine the absolute and relative response rates maintained by orally delivered methadone, cocaine, and their combinations under sequential and concurrent access. Choice between drug combinations containing different concentrations of cocaine was also determined. METHODS: Oral intake of methadone, cocaine, and their combinations was studied with rhesus monkeys during daily 3-h sessions. Lip contact (the operant response) was reinforced by delivery of liquid contingent upon completion of a fixed-ratio schedule. In one series, the drugs and drug combinations were studied sequentially with the water vehicle concurrently available. In the next series, the drugs and drug combinations were concurrently available. In the third series, pairs of drug combinations containing different concentrations of cocaine were also concurrently available. RESULTS: Methadone, cocaine and their combinations functioned as reinforcers. Under sequential access, response rates for the drug combinations and the component drugs were often similar. However, under concurrent access, response rates for the drug combinations were greater than response rates for the component drugs at the highest FR size for each condition. Also, drug combinations containing higher cocaine concentrations were preferred to combinations containing lower cocaine concentrations. CONCLUSIONS: Combinations of methadone and cocaine have relatively greater reinforcing effects than the component drugs, and these greater reinforcing effects are better detected with concurrent measures than with sequential measures.  相似文献   
105.
Acid beta-glucosidase (GCase) is the enzyme deficient in Gaucher disease, an inherited metabolic prototype for enzyme and gene therapy. An 80-kDa mammalian cytoplasmic protein (TCP80/NF90) was discovered to interact with the GCase mRNA coding region and inhibit its translation in vitro and ex vivo. Human TCP80/NF90 is identical to NF90, an IL-2 enhancer protein, and MPP4, an M-phase phosphoprotein. The interaction of recombinant TCP80/NF90 with GCase mRNA was evaluated using the baculovirus/Sf9 insect cell system since these cells lack this protein. Purified recombinant and isolated mammalian cytoplasmic TCP80/NF90 had identical functions including binding of coding regions of selected RNAs and inhibition of their in vitro translation. Individual baculoviruses containing the human TCP80/NF90 cDNA (vSf9/TCP80) and GCase cDNA (vSf9/GCase) were used to co-infect Sf9 cells. The presence of preformed TCP80/NF90 significantly (>87%) inhibited wild-type GCase mRNA translation in these cells, but baculovirus containing a mutant GCase did not. Sf9 cells co-infected with vSf9/TCP80 showed a major reduction of GCase RNA polysome association. These results show that the multifunctional protein, TCP80/NF90, can function in vivo as a translation inhibitory protein and include alterations of mRNA binding to polysomes as a component of its mechanism of action.  相似文献   
106.
The use of the Bene-Anthony Family Relations Test is described and illustrated by three examples of child abuse. This test should be considered in the investigation of definite or suspected cases of abuse and as part of the preparation of court evidence.  相似文献   
107.
Seven eyes containing a copper foreign body for a period from 8 months to 2.5 years were studied histopathologically. Foreign bodies, containing 99% copper, were in all eyes, encapsulated and located in the anterior vitreous. Characteristic features were: formation of foreign body granuloma, especially in later stages, marked fibroblastic proliferation in the vitreous with traction retinal detachment, choroidal effusion with fibrosis and foci of chronic nongranulomatous inflammation in cyclitic membranes, iris, ciliary body and sclera. Copper could be identified by rubeanic acid and rhodanine stainings in the fibrous capsule around foreign body in all eyes, in the lens capsule in one eye and in macrophages in the vitreous and retina in 2 eyes. In eyes with intravitreal haemorrhage macrophages contained also haemosiderin.  相似文献   
108.
Long-term patency of coronary artery bypass grafts (CABG) with internal mammary artery (IMA) is better than with saphenous vein (SV) grafts. To determine if vascular prostacyclin (PGI2) produced by IMA might contribute to the improved outcome, we compared PGI2 generated by IMA and SV fragments from 26 patients undergoing CABG and tested the effect of preoperative, long-term ingestion of of aspirin. Fresh tissues were incubated in buffer +/- 25 mumol/L of sodium arachidonate at 37 degrees C for 5 minutes to stimulate PGI2 production, measured by radioimmunoassay of its major hydrolytic product, 6-keto-PGF1 alpha. Results were expressed in picograms of 6-keto-PGF1 alpha per milligram tissue wet weight for total PGI2 production by vascular segments and picograms per cm2 surface area for endothelial PGI2 production. Endothelial PGI2 production was compared for IMA and SV in template-stirring chambers that exposed only the luminal surface of the vessel, excluding underlying smooth muscle. Endothelial PGI2 production by IMA was significantly higher than production by SV under both basal (mechanical stimulation only 1436 +/- 224 versus 842 +/- 227 pg/cm2, mean +/- SEM, p greater than 0.05) and stimulated (25 mumol/L sodium arachidonate: 3343 +/- 347 versus 2032 +/- 465 pg/cm2, p less than 0.025) conditions in patients not receiving aspirin. For patients receiving aspirin, endothelial PGI2 production by IMA was significantly higher than production by SV in stimulated conditions (1382 +/- 526 versus 683 +/- 124 pg/cm2, p less than 0.05). Histologic examination of the tissue segments revealed intact endothelium after incubation in both IMA and SV. Thus a high capacity for PGI2 synthesis and diminished inhibition of PGI2 after aspirin were demonstrated for IMA compared with SV tissue and may be a factor in the improved patency of IMA grafts.  相似文献   
109.
In the last article in this series, we briefly examined the Principle of Least Effort and the five forms of strain. Strain, you may recall, in physics, describes a change in the volume of a material when a force is applied. Our treatments are a blend of rotation and translation movements of our hands with a changing mix of strains being applied onto the client's tissues. Harnessing and interweaving the various forms of strain with dexterity may aid us in improving our treatment efficacy.In this tissue, we will consider the importance of anchorage and stability in treatment, We will consider a set of ‘House Rules' for improving treatment. In addition, we will explore Bernstein's concept of degrees of freedom.  相似文献   
110.
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