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   318篇
  免费   23篇
  国内免费   1篇
儿科学   2篇
基础医学   5篇
临床医学   30篇
内科学   219篇
神经病学   7篇
特种医学   8篇
外科学   6篇
综合类   3篇
预防医学   8篇
眼科学   2篇
药学   51篇
肿瘤学   1篇
  2023年   3篇
  2022年   1篇
  2021年   9篇
  2020年   1篇
  2019年   5篇
  2018年   10篇
  2017年   4篇
  2016年   6篇
  2015年   5篇
  2014年   8篇
  2013年   14篇
  2012年   11篇
  2011年   18篇
  2010年   8篇
  2009年   6篇
  2008年   16篇
  2007年   17篇
  2006年   18篇
  2005年   18篇
  2004年   8篇
  2003年   6篇
  2002年   8篇
  2001年   3篇
  2000年   9篇
  1999年   8篇
  1997年   5篇
  1996年   4篇
  1992年   7篇
  1991年   8篇
  1990年   9篇
  1989年   11篇
  1988年   8篇
  1987年   12篇
  1986年   13篇
  1985年   7篇
  1984年   10篇
  1983年   3篇
  1982年   4篇
  1981年   1篇
  1980年   3篇
  1977年   3篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1972年   2篇
  1971年   1篇
  1970年   4篇
  1969年   1篇
排序方式: 共有342条查询结果,搜索用时 15 毫秒
1.
Mention of the term sex work often invokes images of marginalized women at risk for HIV infection. Such images, however, are counterintuitive to the functional role intended by the movement that spawned use of the terms ‘sex work’ and ‘sex worker.’ This article looks at the sexual practices of men in urban China to argue for a return to a functional definition of ‘sex work’, which was originally meant to legitimize the role sex plays in work. The progenitors of this movement intended to use ‘sex work’ as a means to legitimize sex as an income-generating activity for women involved in prostitution. I show that sex can also serve a functional role in the work-related duties of men seeking economic and political success in contemporary urban China. Men in China utilize sex as one way for demonstrating the loyalty necessary to access state-owned and controlled resources in a market economy governed under a Leninist system. Overall, the article demonstrates that reclaiming perception of sex work as a functional rather than behavioral category can expand its use for preventing HIV among the broad subset of people who engage in sex as part of their work.  相似文献   
2.
3.
Although a structural feature common to all dopaminergic agonists and antagonists is a side-chain basic amino group, it is unclear whether this moiety binds to the D-1 dopamine (DA) receptor in the charged or uncharged form. To obtain information on this point, we synthesized permanently charged dimethylsulfonium and quaternary ammonium analogs of chlorpromazine and DA and determined whether these compounds can bind to the D-1 receptor by measuring their abilities to inhibit the binding of SCH 23390, a D-1 receptor antagonist. Chlorpromazine and the dimethylsulfonium and trimethylammonium analogs of chlorpromazine were found to inhibit the binding of [3H]SCH 22390, which was maximally inhibited to the same extent by all three compounds. In addition, inhibition curves for the compounds fit a one-site binding model, indicating binding to a single class of sites. However, while the permanently charged chlorpromazine analogs were able to inhibit [3H]SCH-23390 binding, they were considerably less potent than chlorpromazine. DA and dimethyl DA were also able to inhibit [3H]SCH 23390 binding. However, the permanently charged dimethylsulfonium and trimethylammonium analogs of DA were ineffective in inhibiting [3H]SCH 23390 binding. In addition, the permanently uncharged methylsulfide analog did not inhibit binding. These studies show that permanently charged analogs of chlorpromazine can bind to the striatal D-1 receptor, which is consistent with an anionic recognition site on the D-1 receptor that interacts with antagonists in the cationic form. In addition, it appears that a nitrogen atom is not required for binding to the D-1 receptor, since the sulfonium analog of chlorpromazine bound to the receptor to the same extent as chlorpromazine. However, since the permanently charged or uncharged analogs of DA did not bind to the D-1 receptor, it is still unclear as to whether the charged form of a dopaminergic agonist can bind. The lower potency or ineffectiveness of the permanently charged analogs compared to the parent amines (chlorpromazine, DA, dimethyl DA) in binding to the D-1 receptor may reflect the inability of the permanently charged analogs to undergo hydrogen binding with the anionic site of the receptor.  相似文献   
4.
Sudden cardiac death (SCD) may occur in as many as 40% of all patients who suffer from heart failure. This review describes the scope of the problem, risk factors for SCD, the effect of medications used in heart failure on SCD and the potential effect of the implantable cardioverter-defibrillator in primary prevention.  相似文献   
5.
Summary Several compounds have been shown to antagonize the excitation of single neurons produced by excitatory amino acids. This study was designed to determine the effectiveness of these compounds in antagonizing the hypermotility response to excitatory amino acids after intraaccumbens administration. Of the putative antagonists tested, D-aminoadipic acid, diaminopimelic acid and glutamic acid diethyl ester all showed significant inhibitory effects on excitatory amino acid-induced hypermotility while 2-amino-5-phosphonovaleric acid, -D-glutamylglycine, 2-amino-4-phosphonobutyric acid and cis-2,3-piperidine dicarboxylic acid were ineffective. D-Aminoadipic acid decreased N-methyl-aspartic acid-induced hypermotility while having no significant effect on the hypermotility responses induced by kainic or quisqualic acids. Diaminopimelic acid markedly decreased N-methyl-aspartic acid- and kainic acid-induced hypermotility but was totally ineffective on quisqualic acid-induced hypermotility. In contrast to D-aminoadipic acid, glutamic acid diethyl ester antagonized the increase in motility produced by kainic and quisqualic acids but not that produced by N-methyl-aspartic acid. The above data suggests that N-methyl-aspartic acid and quisqualic acid may produce their motor effects through the activation of two different receptors in the nucleus accumbens while kainic acid may mediate its hypermotility response through both N-methyl-aspartic acid and quisqualic acid receptors. However, a third receptor type activated solely by kainic acid cannot be excluded at this time.  相似文献   
6.
The present study was designed to determine whether the environmental context in which amphetamine is administered plays a role in the development of sensitization to the stereotyped behavioral effects of amphetamine in mice. In male CF-1 mice, the dose-response curve for stereotyped behavior elicited by amphetamine was shifted 1.9-fold to the left 48 h after pretreatment with 14 mg/kg amphetamine. Behavioral sensitization only developed in mice that were pretreated in the same or a similar environment as that of the test environment. In addition, when mice were placed in an environment that attenuated the acute expression of stereotyped behavior elicited by the pretreatment dose of amphetamine, sensitization never developed. A further experiment showed that 96% of the mice that expressed stereotypy after the ED50 pretreatment dose of 10 mg/kg amphetamine showed a stereotyped behavioral response to the lesser dose of 7 mg/kg 48 h later, indicating sensitization. In contrast, mice that did not express stereotypy after the ED50 dose of amphetamine failed to show a significant stereotyped behavioral response to amphetamine challenge compared to vehicle-pretreated controls. Therefore, the results indicate that preexposure to a single high dose of amphetamine produces context- and response-dependent sensitization to amphetamine-induced stereotyped behavior.  相似文献   
7.
This study assessed the effects of morphine in the nucleus accumbens on motility elicited by dopaminergic and other classes of drugs, using locomotor activity as the measured response. Dopaminergic stimulants, d-amphetamine (10 micrograms) or dopamine (20 micrograms, 2 hours after nialamide, 200 mg/kg, IP) induced large increases in locomotor activity when injected into the nucleus accumbens. This response was blocked by coadministration of morphine (5 micrograms). The hypermotility response elicited by alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA; 0.5 micrograms), an excitatory amino acid agonist, was also abolished by coadministration of morphine. Increasing the dose of AMPA to 1.5 micrograms partially overcame the morphine block, while increasing the dose of amphetamine to 50 micrograms did not. In other experiments, morphine (5 micrograms) injected into the nucleus accumbens blocked the hypermotility elicited by systemic caffeine (10 mg/kg, SC) or scopolamine (0.5 mg/kg, SC) or intra-accumbal MK-801 (5 micrograms). However, picrotoxin (0.15 or 0.5 microgram) injected into the nucleus accumbens elicited a hypermotility that was not attenuated by coinjection of morphine (5 or 10 micrograms). These data demonstrate that opiate and dopaminergic pathways have competing actions on the regulation of locomotion in the nucleus accumbens. Furthermore, the results with combinations of picrotoxin and morphine suggest the presence of two distinct locomotor pathways or a GABA receptor site "downstream" from the morphine site in a single pathway.  相似文献   
8.
9.
10.
Peak filling rate is an indicator of left ventricular (LV) diastolic function. It is influenced by heart rate, loading conditions, sympathetic nervous system activity, ejection fraction and other factors. To determine the effect of altered loading conditions on peak filling rate, independent of heart rate and sympathetic nervous system activity, 12 patients were studied 3 weeks after orthotopic heart transplantation. Plasma catecholamine level, heart rate and ejection fraction were not changed by any maneuver. Nitroglycerin caused a decrease in pulmonary artery wedge pressure (9 +/- 2 to 6 +/- 1 mm Hg, p less than 0.001) and in absolute peak filling rate (46.0 +/- 3.0 to 42.8 +/- 2.5 kcts/s, p less than 0.01), but no change in normalized peak filling rate. Volume infusion increased pulmonary artery wedge pressure (9 +/- 2 to 12 +/- 2 mm Hg, p less than 0.001) and absolute peak filling rate (46.0 +/- 3.0 to 51.5 +/- 5.3 kcts/s, p less than 0.01), but peak filling rate normalized to stroke volume was unchanged. During nitroglycerin and volume infusions, there was a high correlation between changes in pulmonary artery wedge pressure and absolute peak filling rate (r = 0.82, p less than 0.001). With normalization of peak filling rate, these variables correlated less well. With methoxamine, 4 patients demonstrating systolic dysfunction had a decrease in absolute and normalized peak filling rate despite a large increase in pulmonary artery wedge pressure. The other 8 patients without systolic dysfunction had an increase in pulmonary artery wedge pressure with increased absolute but unchanged normalized peak filling rate.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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