全文获取类型
收费全文 | 8846篇 |
免费 | 954篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 77篇 |
儿科学 | 296篇 |
妇产科学 | 187篇 |
基础医学 | 1214篇 |
口腔科学 | 283篇 |
临床医学 | 1009篇 |
内科学 | 1680篇 |
皮肤病学 | 93篇 |
神经病学 | 891篇 |
特种医学 | 351篇 |
外科学 | 1191篇 |
综合类 | 349篇 |
一般理论 | 7篇 |
预防医学 | 972篇 |
眼科学 | 270篇 |
药学 | 542篇 |
中国医学 | 3篇 |
肿瘤学 | 413篇 |
出版年
2021年 | 131篇 |
2020年 | 106篇 |
2019年 | 151篇 |
2018年 | 155篇 |
2017年 | 133篇 |
2016年 | 113篇 |
2015年 | 140篇 |
2014年 | 192篇 |
2013年 | 334篇 |
2012年 | 399篇 |
2011年 | 423篇 |
2010年 | 241篇 |
2009年 | 225篇 |
2008年 | 367篇 |
2007年 | 388篇 |
2006年 | 384篇 |
2005年 | 369篇 |
2004年 | 350篇 |
2003年 | 280篇 |
2002年 | 312篇 |
2001年 | 283篇 |
2000年 | 280篇 |
1999年 | 265篇 |
1998年 | 114篇 |
1997年 | 113篇 |
1996年 | 112篇 |
1995年 | 93篇 |
1994年 | 92篇 |
1993年 | 86篇 |
1992年 | 206篇 |
1991年 | 184篇 |
1990年 | 210篇 |
1989年 | 221篇 |
1988年 | 205篇 |
1987年 | 159篇 |
1986年 | 158篇 |
1985年 | 165篇 |
1984年 | 116篇 |
1983年 | 116篇 |
1982年 | 78篇 |
1981年 | 67篇 |
1979年 | 117篇 |
1978年 | 100篇 |
1977年 | 80篇 |
1976年 | 69篇 |
1975年 | 62篇 |
1974年 | 71篇 |
1973年 | 95篇 |
1972年 | 87篇 |
1971年 | 75篇 |
排序方式: 共有9828条查询结果,搜索用时 0 毫秒
81.
Detection of Campylobacter pylori DNA by hybridisation with non-radioactive probes in comparison with a 32P-labelled probe 总被引:7,自引:0,他引:7
A dot-blot hybridisation assay for the detection of Campylobacter pylori was used to compare a 32P-labelled probe with two biotinylated probes and a sulphonated probe. The minimum amount of pure C. pylori DNA that could be detected by the 32P-labelled probe was 100 pg, which corresponded to 5 x 10(4) bacteria. A biotin-labelled DNA (biotin-DNA) probe together with the BluGeneTM detection system produced by Bethesda Research Laboratories (BRL), and a sulphonated probe and ChemiprobeTM detection system (Orgenics) gave similar levels of sensitivity; nylon membranes could be used with both these non-radioactive detection systems. However, a photobiotin-labelled DNA (photobiotin-DNA) probe and detection system produced by Biotechnology Research Enterprises S.A. (BRESA) gave optimum results only with nitrocellulose membranes, and was quantitatively 100 times less sensitive than the other types of probe. The detection systems for the biotin-DNA and photobiotin-DNA probes produced non-specific reactions with crude bacterial blots of heterologous organisms; these non-specific reactions could be removed by treating the dot blots with proteinase K, but not by treatment with RNAase. The sulphonated probe and detection system did not give any reaction with heterologous organism blots. 相似文献
82.
In postnatal day 7 rats, a unilateral intrastriatal injection of 12.5 nmol of N-methyl-D-aspartate (NMDA) reproducibly injures the ipsilateral striatum, adjacent hippocampus and overlying cortex. The severity of injury can be quantified by comparing cerebral hemisphere weights in animals sacrificed 5 days after the injection. Co-injection of NMDA and the glycine receptor antagonists kynurenic acid (KYN) or 7-chlorokynurenic acid (7-CKA) reduced the severity of NMDA-induced damage in a dose-dependent fashion. One hundred nmol of KYN with 12.5 nmol of NMDA reduced average % damage from 19.3 +/- 0.9% (n = 9) to 2.3 +/- 0.5% (n = 6), P less than 0.001, ANOVA. Co-injection of 40 nmol of 7-CKA with 12.5 nmol of NMDA (n = 6) reduced average % damage from 17.1 +/- 1.6% (n = 15) to 3.0 +/- 0.6%, P less than 0.001, ANOVA. Concurrent injection of 1000 nmol glycine with 5 nmol NMDA did not increase the extent of NMDA-induced damage. Our results demonstrate that glycine receptor antagonists attenuate NMDA-induced brain injury in vivo. 相似文献
83.
84.
This report investigated differential cerebral impairment on the Luria-Nebraska Neuropsychological Battery in schizophrenia, schizoaffective, and depressive disorders (N = 106). Results indicated impaired tactile-stereognostic processing in schizoaffective and depressive disorder patients and verbal memory deficits in the schizophrenic and schizoaffective disorder patients. These findings question the specificity of functional neuropsychological deficit areas in schizophrenia and depression. 相似文献
85.
Harrod KS Jaramillo RJ Rosenberger CL Wang SZ Berger JA McDonald JD Reed MD 《American journal of respiratory cell and molecular biology》2003,28(4):451-463
Although epidemiologic data strongly suggest a role for inhaled environmental pollutants in modulating the susceptibility to respiratory infection in humans, the underlying cellular and molecular mechanisms have not been well studied in experimental systems. The current study assessed the impact of inhaled diesel engine emissions (DEE) on the host response in vivo to a common pediatric respiratory pathogen, respiratory syncytial virus (RSV). Using a relatively resistant mouse model of RSV infection, prior exposure to either 30 microg/m3 particulate matter (PM) or 1,000 microg/m3 PM of inhaled DEE (6 h/d for seven consecutive days) increased lung inflammation to RSV infection as compared with air-exposed RSV-infected C57Bl/6 mice. Inflammatory cells in bronchoalveolar lavage fluid were increased in a dose-dependent manner with regard to the level of DEE exposure, concomitant with increased levels of inflammatory mediators. Lung histology analysis indicated pronounced peribronchial and peribronchiolar inflammation concordant with the level of DEE exposure during infection. Mucous cell metaplasia was markedly increased in the airway epithelium of DEE-exposed mice following RSV infection. Interestingly, both airway and alveolar host defense and immunomodulatory proteins were attenuated during RSV infection by prior DEE exposure. DEE-induced changes in inflammatory and lung epithelial responses to infection were associated with increased RSV gene expression in the lungs following DEE exposure. These findings are consistent with the concept that DEE exposure modulates the lung host defense to respiratory viral infections and may alter the susceptibility to respiratory infections leading to increased lung disease. 相似文献
86.
Jaccard J McDonald R Wan CK Guilamo-Ramos V Dittus P Quinlan S 《Journal of health psychology》2004,9(6):699-712
Accuracy of recall of the number of sexual partners individuals had over a period of one month, three months, six months and one year was studied in a group of 285 young, single, heterosexual adults. Self-reports of the number of partners were obtained on a weekly basis and then compared with recall of behavior over longer time periods that overlapped the weekly measures. For individuals who claimed abstinence or who claimed to be monogamous, accuracy of recall was relatively high, especially at the shorter time frames. Level of education was related to accuracy for claimed abstainers, such that lower levels of education were associated with lower accuracy of recall. Accuracy rates for individuals who reported having multiple sexual partners tended to be lower and were found to be related to one's propensity to engage in casual sex. 相似文献
87.
Pratt W Reddy MC McDonald DW Tarczy-Hornoch P Gennari JH 《Journal of biomedical informatics》2004,37(2):128-137
Many information systems have failed when deployed into complex health-care settings. We believe that one cause of these failures is the difficulty in systematically accounting for the collaborative and exception-filled nature of medical work. In this methodological review paper, we highlight research from the field of computer-supported cooperative work (CSCW) that could help biomedical informaticists recognize and design around the kinds of challenges that lead to unanticipated breakdowns and eventual abandonment of their systems. The field of CSCW studies how people collaborate with each other and the role that technology plays in this collaboration for a wide variety of organizational settings. Thus, biomedical informaticists could benefit from the lessons learned by CSCW researchers. In this paper, we provide a focused review of CSCW methods and ideas-we review aspects of the field that could be applied to improve the design and deployment of medical information systems. To make our discussion concrete, we use electronic medical record systems as an example medical information system, and present three specific principles from CSCW: accounting for incentive structures, understanding workflow, and incorporating awareness. 相似文献
88.
The development of defensive reaction in the ant Novomessor albisetosus against predation by army ants is studied in the laboratory and field. Two clusters of behavior emerge: escape with or without the brood, and aggressive defense. Escape develops specifically as a reaction against army ants and not in the presence of other ant species. Other behaviors develop with varying degrees of specificity toward army ants. All behaviors develop with age in workers isolated from experience with army ants. However, evidence is presented suggesting that experience with army ants alters the course of this development. 相似文献
89.
A whole trout preparation (Salmo gairdneri) externally ventilated with water and internally perfused with artificial medium via a cardiac pump is discribed for the study of O2 exchange and vascular resistance. As cardiac output (Q) was raised, ventral and dorsal aortic pressures increased while branchial (Rg) and systemic (Rs) vascular resistances fell, reflecting considerable passive distensibility. Arterial oxygenation was negative at low Qs due to significant internal O2 demand by the gill tissue, but increased to zero or positive values at intermediate Qs, and eventually declined at high Qs because of transit time limitation. O2 uptake from the ventilatory flow rose with increasing Q. Epinephrine (10(-5) M) decreased Rg, increased Rs, and enhanced arterial oxygenation. Artificial elevation of dorsal aortic pressure decreased Rg but did not affect arterial oxygenation. A 10-fold elevation of ventilatory flow increased arterial oxygenation but did not alter Rg or Rs. Endogenous metabolism of branchial tissue accounted for 11.7% of resting O2 uptake in vivo, and comprised an internal component taking O2 from perfusion flow and an external component drawing O2 from ventilatory flow. 相似文献
90.
P.A. McDonald 《Physiology & behavior》1982,29(5):813-818
Sham-operated male doves displayed greater nesting activity under long days (16L:8D) than under short days (8L:16D). This difference was abolished by pinealectomy—the activity of long-day pinealectomized birds dropped to a level comparable to that seen on short days. Removal of the pineal had no effect under the short photoperiod. These results are not due to changes in peripheral androgen production as castrated, testosterone-implanted males also exhibited higher levels of nest-building on long days if sham-operated, but not if they were pinealectomized. Neither treatment had a significant effect on courtship or copulatory behavior. It is suggested that the pineal mediates the stimulatory effect of long photoperiods on hormonally-induced nest-building in doves. 相似文献