全文获取类型
收费全文 | 54772篇 |
免费 | 4306篇 |
国内免费 | 993篇 |
专业分类
耳鼻咽喉 | 211篇 |
儿科学 | 716篇 |
妇产科学 | 2082篇 |
基础医学 | 5541篇 |
口腔科学 | 880篇 |
临床医学 | 5284篇 |
内科学 | 7314篇 |
皮肤病学 | 281篇 |
神经病学 | 3217篇 |
特种医学 | 1486篇 |
外国民族医学 | 2篇 |
外科学 | 3750篇 |
综合类 | 5880篇 |
现状与发展 | 5篇 |
一般理论 | 5篇 |
预防医学 | 9773篇 |
眼科学 | 393篇 |
药学 | 7894篇 |
53篇 | |
中国医学 | 3325篇 |
肿瘤学 | 1979篇 |
出版年
2024年 | 145篇 |
2023年 | 812篇 |
2022年 | 1466篇 |
2021年 | 2193篇 |
2020年 | 2377篇 |
2019年 | 1809篇 |
2018年 | 1720篇 |
2017年 | 1846篇 |
2016年 | 1825篇 |
2015年 | 1852篇 |
2014年 | 4286篇 |
2013年 | 4358篇 |
2012年 | 3704篇 |
2011年 | 3945篇 |
2010年 | 3152篇 |
2009年 | 2854篇 |
2008年 | 2694篇 |
2007年 | 2476篇 |
2006年 | 2164篇 |
2005年 | 1790篇 |
2004年 | 1471篇 |
2003年 | 1396篇 |
2002年 | 1151篇 |
2001年 | 923篇 |
2000年 | 727篇 |
1999年 | 650篇 |
1998年 | 531篇 |
1997年 | 514篇 |
1996年 | 504篇 |
1995年 | 535篇 |
1994年 | 406篇 |
1993年 | 403篇 |
1992年 | 352篇 |
1991年 | 309篇 |
1990年 | 321篇 |
1989年 | 272篇 |
1988年 | 268篇 |
1987年 | 238篇 |
1986年 | 208篇 |
1985年 | 262篇 |
1984年 | 214篇 |
1983年 | 147篇 |
1982年 | 160篇 |
1981年 | 134篇 |
1980年 | 123篇 |
1979年 | 82篇 |
1978年 | 65篇 |
1977年 | 42篇 |
1976年 | 68篇 |
1975年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
151.
本文介绍用国产酶免定量药盒测定血、尿样中hCG含量的一种ELISA方法。该方法特异性好、经济可靠而且简便快捷,适用于运动员尿样的兴奋剂检测。文中还报道了该方法应用于测定两例志愿者注射hCG后的血、尿样及国际奥委会医学委员会1994年水平考试和1995年资格复试hCG阳性尿样的结果,并讨论了测得值与其它试剂盒测定结果的差异及原因。 相似文献
152.
W N Kühn-Velten 《Andrologia》1992,24(2):109-111
In addition to the well-known control circuits involved in the regulation and adaptation of testicular androgen biosynthesis, it is proposed that two new control strategies are involved in the maintenance of steady-state testosterone secretion rates by testicular Leydig cells. Cytochrome P450XVII (steroid-17 alpha-monooxygenase/steroid-17,20-lyase), one key enzyme in steroid hormone biosynthesis, responds to external human choriogonadotropin stimulation with an oxygen-dependent and substrate flux-dependent inactivation and decomposition, and increased substrate availability decreases the efficiency of androgen formation in favour of abortive intermediate leakage. These results are discussed as a paradigm of substrate-dependent modulation of cytochrome P450 activities. 相似文献
153.
Induction of type II collagen-specific antibody production in blood lymphocyte cultures of rhesus monkeys (Macaca mulatta) with collagen-induced arthritis using the immobilized native antigen.
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Peripheral blood mononuclear cells (PBMC) from Rhesus monkeys previously immunized with bovine type II collagen to induce arthritis were cultured with the same antigen. Because the native protein is poorly soluble in culture medium a heating step is often used. The antigen in this form induced PBMC proliferation, but epitopes for the induction of antibody production and arthritis were lost. To keep the native protein intact it was coated on affigel beads. With the immobilized antigen specific antibody production could be induced. 相似文献
154.
155.
Temporary closure of the abdominal wall (laparostomy) 总被引:2,自引:0,他引:2
A. Schachtrupp V. Fackeldey U. Klinge J. Hoer A. Tittel C. Toens V. Schumpelick 《Hernia》2002,6(4):155-162
The definitive closure of the abdominal wall, i.e., a closure of the fascial layer and skin may not be favorable in the treatment
of numerous surgical conditions, e.g., peritonitis, trauma, or mesenteric ischemia. In these cases, the abdominal wall is
temporarily closed, and a laparostomy is created to facilitate re-exploration or to prevent abdominal compartment syndrome.
Regarding the technique and material used for the temporary closure, no prospective randomized data exists, but mesh materials
are commonly used. They provide drainage of infectious material, permit visual control of the underlying viscera, facilitate
access to the abdominal wall, preserve the fascial margin, enable healing by secondary intention, and allow mobilization of
the patient. In the case of decreasing intra-abdominal pressure, meshes can be trimmed to centralize the rectus muscle and
to facilitate definitive closure. Non-absorbable meshes have been frequently reported to cause enteric fistulae and persistent
infection necessitating mesh explantation. While these infectious complications appear to occur less frequently with the use
of absorbable materials, these meshes will finally lead to an incisional hernia, requiring repair with non-absorbable mesh
after a period of 6–12 months. Nevertheless, in the complex situation requiring a temporary abdominal wall closure, use of
absorbable mesh material is common and represents the state of the art.
Electronic Publication 相似文献
156.
Annette Anderton 《Journal of human nutrition and dietetics》1994,7(1):53-60
The HACCP (hazard analysis critical control point) concept is now widely applied in the food industry and provides a structured and critical approach to the identification and control of hazards that may affect food safety. It has shifted the emphasis for control from retrospective end-product testing to the effective control of raw materials and key processing operations.
This paper discusses how the HACCP approach can be applied to enteral feeding. This involves each unit assembling a multidisciplinary team of personnel involved in enteral feeding. This team will then carry out a detailed analysis of the process from selection of ingredients and feeding systems through to consumption of the feed by the patient by constructing a flow chart that relates specifically to each unit. They can then identify and assess the hazards associated with the handling of the product at each stage in the process. This will enable them to identify the points where control over an identified hazard can be achieved (critical control points, CCP) such as quality of ingredients, design of administration systems, preparation and distribution of the feeds and the procedures involved in the assembly and manipulation of the systems. Control and monitoring procedures can then be specified and implemented at relevant stages in the process. The major strengths of the HACCP procedure are that it entails a team effort from key personnel involved in the full range of activities associated with the product and each detailed analysis is specific to each unit's practices and resources and can be continually reviewed and modified in response to changing circumstances. 相似文献
This paper discusses how the HACCP approach can be applied to enteral feeding. This involves each unit assembling a multidisciplinary team of personnel involved in enteral feeding. This team will then carry out a detailed analysis of the process from selection of ingredients and feeding systems through to consumption of the feed by the patient by constructing a flow chart that relates specifically to each unit. They can then identify and assess the hazards associated with the handling of the product at each stage in the process. This will enable them to identify the points where control over an identified hazard can be achieved (critical control points, CCP) such as quality of ingredients, design of administration systems, preparation and distribution of the feeds and the procedures involved in the assembly and manipulation of the systems. Control and monitoring procedures can then be specified and implemented at relevant stages in the process. The major strengths of the HACCP procedure are that it entails a team effort from key personnel involved in the full range of activities associated with the product and each detailed analysis is specific to each unit's practices and resources and can be continually reviewed and modified in response to changing circumstances. 相似文献
157.
The relationship of perceived control over daily uplifts and hassles to depression and restraint was examined in a sample of 140 middle-class sixth graders. Results indicated that greater control over uplifts was associated with better functioning and lower control over hassles with poorer functioning, even after partialing out the respective number of uplifts and hassles reported. Moreover, when directly compared, control over uplifts showed more powerful associations with adaptational outcomes than did control over hassles. In a separate analysis, the number of uplifts over which children reported high control showed opposite relationships to adaptational outcomes than did the number of uplifts over which children reported low control. A different pattern appeared for hassles. Although the number of hassles with low control was associated with poorer functioning, the number of hassles over which children had high control was unrelated to adaptational outcomes. The possibility that control operates somewhat differently for positive and negative events is discussed.This research was supported by a grant to the second author from the Stanford Center for the Study of Families, Children and Youth. The authors are grateful to Rachelle Hacket for data analysis, Tom Gehring for data collection, and Susan Nolen-Hoeksema for critical comments. 相似文献
158.
While much research has been devoted to the implementation and application of Volterra and Wiener functional series expansions
in the identification and characterization of biological systems, little effort has been focused on the fundamental problem
of interpreting the resulting kernels. This paper describes the application of the series to the components of a known model
of the human pupil control system. As more complicated elements are put together, insight into kernel interpretation is built
up incrementally until the total system is identified. Practical limitations and methods are also discussed. 相似文献
159.
Summary Estrogen has an important role in stimulating the growth of breast carcinomas. Inhibition of estrogen production is therefore a logical treatment strategy. A number of selective inhibitors have been developed against aromatase, a cytochrome P-450 enzyme which catalyzes the rate limiting step in the biosynthesis of estrogens. The mechanisms of the aromatase reaction, current knowledge of the enzyme, and regulation of its expression are discussed as the basis for inhibitor development. Two classes of aromatase inhibitors, steroidal and non-steroidal compounds, are now coming into use. Among the steroid substrate analogues, 4-hydroxyandrostenedione (4-OHA) has been shown to be effective in breast cancer patients with advanced disease and was recently approved for treatment in the United Kingdom. Several different classes of compounds which act as aromatase inhibitors are currently in clinical trials and should provide breast cancer patients with a number of treatment options. Among these are highly potent and selective non-steroidal inhibitors which have recently been found to suppress plasma and urinary estrogens over 95% in breast cancer patients. The potency of these newer aromatase inhibitors provides the opportunity to determine whether complete suppression of estrogen production and action will result in enhanced tumor regression. 相似文献
160.
Eight patients who developed severe ovarian hyperstimulation syndrome (OHSS) were identified among 1302 patients undergoing in-vitro fertilization (IVF) over a 1 year period (prevalence of 0.6%); 63% had ultrasonically diagnosed polycystic ovaries (PCO) and 75% were undergoing their first attempt at IVF. Pretreatment with a superactive luteinizing hormone-releasing hormone (LHRH) analogue significantly increased the prevalence of severe OHSS (1.1% versus 0.2%, P less than 0.05) compared with ovarian stimulation with clomiphene citrate and human menopausal gonadotrophin (HMG). The mean serum oestradiol concentration on the day of human chorionic gonadotrophin (HCG) administration was 8200 +/- 2300 pmol/l. A mean of 19.6 +/- 6.8 follicles had been aspirated and 13.1 +/- 7.7 oocytes recovered at transvaginal ultrasound-directed oocyte recovery. All patients had an embryo transfer and luteal support in the form of HCG. The clinical pregnancy rate was 88%, multiple pregnancy rate 71% and implantation rate 63.5 +/- 41.3%. In a group of seven patients who were hospitalized for moderate OHSS during the same period, peak oestradiol levels were significantly lower than in those with severe OHSS (P less than 0.05). Of the group with moderate OHSS, 57% had PCO, the clinical pregnancy rate was 100% and multiple pregnancy rate 43%. Patients with ultrasound-diagnosed PCO have an increased risk of developing OHSS and the dose of HMG administered to them should be minimized. In patients at risk of developing OHSS, progesterone instead of HCG should be used for luteal support. Transfer of a maximum of two embryos or freezing all embryos for transfer in a subsequent cycle may reduce the likelihood of multiple pregnancy. 相似文献