全文获取类型
收费全文 | 9040篇 |
免费 | 776篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 417篇 |
妇产科学 | 180篇 |
基础医学 | 1433篇 |
口腔科学 | 325篇 |
临床医学 | 973篇 |
内科学 | 1609篇 |
皮肤病学 | 150篇 |
神经病学 | 1058篇 |
特种医学 | 226篇 |
外科学 | 1001篇 |
综合类 | 206篇 |
一般理论 | 10篇 |
预防医学 | 804篇 |
眼科学 | 111篇 |
药学 | 711篇 |
中国医学 | 30篇 |
肿瘤学 | 575篇 |
出版年
2021年 | 135篇 |
2020年 | 96篇 |
2019年 | 141篇 |
2018年 | 149篇 |
2017年 | 120篇 |
2016年 | 132篇 |
2015年 | 131篇 |
2014年 | 186篇 |
2013年 | 292篇 |
2012年 | 437篇 |
2011年 | 410篇 |
2010年 | 269篇 |
2009年 | 214篇 |
2008年 | 419篇 |
2007年 | 380篇 |
2006年 | 375篇 |
2005年 | 369篇 |
2004年 | 341篇 |
2003年 | 359篇 |
2002年 | 325篇 |
2001年 | 295篇 |
2000年 | 281篇 |
1999年 | 237篇 |
1998年 | 108篇 |
1997年 | 94篇 |
1996年 | 72篇 |
1995年 | 89篇 |
1994年 | 69篇 |
1993年 | 68篇 |
1992年 | 182篇 |
1991年 | 215篇 |
1990年 | 157篇 |
1989年 | 200篇 |
1988年 | 215篇 |
1987年 | 251篇 |
1986年 | 200篇 |
1985年 | 232篇 |
1984年 | 137篇 |
1983年 | 94篇 |
1982年 | 77篇 |
1981年 | 79篇 |
1980年 | 66篇 |
1979年 | 106篇 |
1978年 | 107篇 |
1977年 | 90篇 |
1976年 | 66篇 |
1975年 | 75篇 |
1974年 | 77篇 |
1973年 | 72篇 |
1972年 | 72篇 |
排序方式: 共有9842条查询结果,搜索用时 15 毫秒
41.
A M Reynolds S P Zadow R Scicchitano R D McEvoy 《The American review of respiratory disease》1992,145(1):80-84
We have previously shown that airway hypocapnia induced bronchoconstriction in the guinea pig lung by releasing tachykinins. To examine whether airway hypocapnia could also cause an increase in airway microvascular leakage, a tracheal segment was isolated in vivo in anesthetized guinea pigs and unidirectionally ventilated (200 ml/min) for 1 h with fully conditioned air (0% CO2) or isocapnic gas (5% CO2). The lungs were ventilated through a distally placed tracheal cannula. Microvascular leakage was quantitated by the injection of Evans blue (EB) and its extraction from the tracheal segment. EB extravasation was increased in tracheae exposed to 0% CO2 (52.3 +/- 2.0 micrograms/g wet tissue) compared with tracheae exposed to 5% CO2 (26.4 +/- 2.9 micrograms/g; p less than 0.05) and to tracheae from spontaneously breathing guinea pigs (25.2 +/- 2.3 micrograms/g; p less than 0.05). Groups of animals in which trachea were unidirectionally ventilated with 0% CO2 were then pretreated with a range of drugs in an attempt to determine the mediators responsible for the microvascular leakage with 0% CO2. Capsaicin and morphine pretreatment did not significantly alter 0% CO2-induced EB extravasation, and phosphoramidon prevented rather than increased extravasation, suggesting that tachykinins did not play a role. The hypocapnia-induced increase in microvascular leakage was, however, prevented by indomethacin pretreatment and significantly attenuated by dazmegrel, a thromboxane synthetase inhibitor. We conclude that airway hypocapnia causes microvascular leakage in the guinea pig trachea and that this effect is mediated by prostaglandins and/or thromboxane. 相似文献
42.
43.
Sydney Reynolds 《British medical journal》2003,327(7423):1112
44.
45.
R Vogel R P Crick K B Mills P M Reynolds W Sass C M Clineschmidt R Tipping 《Ophthalmology》1992,99(10):1505-1511
BACKGROUND: Relatively few studies have been conducted linking decreasing intraocular pressure (IOP) to preservation of visual field. This investigation was conducted to determine if this link could be made and to compare the long-term effect of two ocular hypotensive agents on preservation of visual field. METHODS: In an observer-masked study, 189 patients with primary open-angle glaucoma received either timolol or pilocarpine by random allocation. The dose of antiglaucoma agent was increased from 0.25% to 0.5% twice daily for timolol or from 2% to 4% four times daily for pilocarpine if the initial IOP response was inadequate. After an on-treatment baseline, visual fields were followed every 4 months for 2 years using the Octopus program 32. RESULTS: Compared with timolol, significantly more patients receiving pilocarpine discontinued use because of inadequate IOP control (P < or = 0.01). By comparing the mean visual field scores, it can be seen that the pilocarpine group had a significantly worse score at all timepoints from month 4 to month 24. The pilocarpine group also had a greater mean number of test loci with decreased sensitivity of 5 or more decibels (dB) at all timepoints. The mean within-patient regression slope for timolol was 0.01 dB/month and for pilocarpine was -0.06 dB/month (P < 0.01). The study has shown that over a 2-year period, patients treated with pilocarpine 2% or 4% four times daily experienced a significantly greater visual field deterioration than that seen in patients receiving either 0.25% or 0.5% timolol twice daily. CONCLUSION: Although these data do not support a link between lowering of IOP and visual field preservation, treatment with timolol was associated with significantly less visual field loss than treatment with pilocarpine. 相似文献
46.
47.
A variety of environmentally persistent chemicals, including some phthalate plasticizers, are weakly estrogenic. 总被引:39,自引:11,他引:28 下载免费PDF全文
S Jobling T Reynolds R White M G Parker J P Sumpter 《Environmental health perspectives》1995,103(6):582-587
Sewage, a complex mixture of organic and inorganic chemicals, is considered to be a major source of environmental pollution. A random screen of 20 organic man-made chemicals present in liquid effluents revealed that half appeared able to interact with the estradiol receptor. This was demonstrated by their ability to inhibit binding of 17 beta-estradiol to the fish estrogen receptor. Further studies, using mammalian estrogen screens in vitro, revealed that the two phthalate esters butylbenzyl phthalate (BBP) and di-n-butylphthalate (DBP) and a food antioxidant, butylated hydroxyanisole (BHA) were estrogenic; however, they were all less estrogenic than the environmental estrogen octylphenol. Phthalate esters, used in the production of various plastics (including PVC), are among the most common industrial chemicals. Their ubiquity in the environment and tendency to bioconcentrate in animal fat are well known. Neither BBP nor DBP were able to act as antagonists, indicating that, in the presence of endogenous estrogens, their overall effect would be cumulative. Recently, it has been suggested that environmental estrogens may be etiological agents in several human diseases, including disorders of the male reproductive tract and breast and testicular cancers. The current finding that some phthalate compounds and some food additives are weakly estrogenic in vitro, needs to be supported by further studies on their effects in vivo before any conclusions can be made regarding their possible role in the development of these conditions. 相似文献
48.
Desmond FS Cormack RMN RGN MPhil DipEd PhD DipN Honorary Reader in Health Nursing William Reynolds RMN RNT RGN MPhil Senior Tutor 《Journal of advanced nursing》1992,17(12):1472-1478
Arguably, nursing, like all health care disciplines, is an applied science. Essentially, this refers to the application of theory in order to understand and respond to the health problems of clients. These theories may be drawn (borrowed) from any applied science, or generated inductively from clinical nursing practice. Alternatively, nurses may attempt to apply deductive theory (global theoretical frameworks) known as nursing models. In this paper, all theoretical approaches, irrespective of origin, are referred to as models used by nurses. Thirteen criteria by which clinicians, and others, can evaluate the clinical and practical utility of models used by nurses which are expressed in the form of questions are identified and discussed. The criteria are an extension, both in detail and in number, of those developed by Reynolds and Cormack and subsequently applied by those writers to the Johnson Behavioural System Model of Nursing. The value, or otherwise, of individual models, or of models in general, will not be discussed in this paper. However, the authors propose that if the evaluation criteria described here are applied to existing models, serious deficits will be identified in relation to their clinical and practical utility. 相似文献
49.
Expression of proliferating cell nuclear antigen (PCNA) in gastric carcinoma: no evidence for prognostic value. 总被引:3,自引:0,他引:3 下载免费PDF全文
D C Mangham D C Rowlands K M Newbold G M Reynolds J W Fielding M T Hallissey 《Journal of clinical pathology》1994,47(5):473-474
It has been proposed that immunostaining with PC10, a monoclonal antibody against proliferating cell nuclear antigen (PCNA), is of prognostic value in gastric carcinoma. Gastric carcinomas from a series of 90 patients in whom survival data were known have been studied. There was no relation between the degree of PC10 immunostaining assessed semiquantitatively and survival. 相似文献
50.
J T Benjamin M D Dickens R F Ford D L Hawkes C W Machen V A Perriello D N Reynolds 《Clinical pediatrics》1991,30(2):74-76
Free erythrocyte protoporphyrin (FEP) and hemoglobin (Hgb) concentrations were tested in 790 children in a private pediatric office; results were compared to those obtained in 1984. Only 16 children (2%) had abnormal FEPs in 1990 compared to 76 children (9.6%) in the earlier study. The mean FEP in the normal group also decreased significantly in each age group studied. The hemoglobin concentrations were not significantly different in most of the age groups studied. Screening for iron deficiency in our pediatric practice by determining hemoglobin and FEP concentrations had a much lower yield in 1990 than in 1984. 相似文献