全文获取类型
收费全文 | 6077篇 |
免费 | 512篇 |
国内免费 | 410篇 |
专业分类
耳鼻咽喉 | 45篇 |
儿科学 | 76篇 |
妇产科学 | 41篇 |
基础医学 | 621篇 |
口腔科学 | 67篇 |
临床医学 | 824篇 |
内科学 | 1025篇 |
皮肤病学 | 98篇 |
神经病学 | 276篇 |
特种医学 | 253篇 |
外科学 | 749篇 |
综合类 | 990篇 |
预防医学 | 373篇 |
眼科学 | 164篇 |
药学 | 722篇 |
1篇 | |
中国医学 | 314篇 |
肿瘤学 | 360篇 |
出版年
2024年 | 18篇 |
2023年 | 110篇 |
2022年 | 208篇 |
2021年 | 291篇 |
2020年 | 189篇 |
2019年 | 189篇 |
2018年 | 193篇 |
2017年 | 171篇 |
2016年 | 170篇 |
2015年 | 263篇 |
2014年 | 287篇 |
2013年 | 335篇 |
2012年 | 415篇 |
2011年 | 410篇 |
2010年 | 274篇 |
2009年 | 234篇 |
2008年 | 271篇 |
2007年 | 397篇 |
2006年 | 322篇 |
2005年 | 309篇 |
2004年 | 207篇 |
2003年 | 204篇 |
2002年 | 167篇 |
2001年 | 140篇 |
2000年 | 150篇 |
1999年 | 137篇 |
1998年 | 112篇 |
1997年 | 105篇 |
1996年 | 92篇 |
1995年 | 93篇 |
1994年 | 74篇 |
1993年 | 41篇 |
1992年 | 39篇 |
1991年 | 45篇 |
1990年 | 44篇 |
1989年 | 52篇 |
1988年 | 47篇 |
1987年 | 30篇 |
1986年 | 25篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1958年 | 16篇 |
1955年 | 4篇 |
排序方式: 共有6999条查询结果,搜索用时 15 毫秒
41.
目的 观察控制性降压结合急性高容血液稀释 (AHH)对脑膜瘤手术的安全性及减少出血量和术后血红蛋白 (Hb)、红细胞比积 (Hct)的影响。 方法 择期脑膜瘤手术病人 2 0例 ,随机分成控制性降压结合AHH组 (Ⅰ组 ,n =10 )和对照组 (Ⅱ组 ,n =10 ) ,两组均采用气管内全麻。Ⅰ组病人于气管插管后手术开始前完成AHH并进行控制性降压。比较两组病人术中出血量、输血量和术后Hb、Hct变化。 结果 Ⅰ组病人术中平均出血量 (5 44± 92 )ml ,比Ⅱ组病人的 (10 72± 182 )ml减少 49 7% ;Ⅱ组病人平均输血量 (62 0± 112 )ml ,Ⅰ组病人则完全避免输异体血。两组病人术毕均有轻度贫血 ,但仍在安全水平范围内。 结论 控制性降压结合急性高容血液稀释可安全应用于脑膜瘤手术 ,对有指征病人的使用可避免术中输异体血 相似文献
42.
43.
Effectsofhammerheadribozyme(RCP)onHBVPgeneinvitroGanLixia(甘立霞),WangPing(王平),ZhuXihua(朱锡华),DongYanlin(董燕麟),HouYunde(侯云德)(Depar... 相似文献
44.
为探讨新婚前后人群对避孕方法(特别是紧急避孕方法)的知识、态度和使用以及新婚前后人群对紧急避孕的需求及对推广EC的意愿的建议。采用描述性流行病学研究方法,以郑州市新婚学校为研究现场,直接收集第一手数据。采用EPI INF6.04软件包,和SPSS7.5 FOR WINDOW95软件包,进行数据处理、统计与分析。统计分析的主要指标有:频数分布,单因素分析,logistic多元回归分析等。结果平均年龄26.41岁,女性占49.4%。在第一次同房时,仅有46.4%的人使用过避孕方法。第一次同房时最常用的避孕方法是避孕套(76.1%)。在女性应答者中,25岁以下开始同房者占76.6%,有9.3%的人有过人工流产史。88.2%的人每周有1~6次同房。有43.2%的人听说过EC方法,有35.9%的人听说过紧急避孕片,有29.9%的人知道使用EC片有时间限制,有24.7%的人听说过上环可作为紧急避孕方法,有17.4%的人知道上环紧急避孕方法有时间限制。仅有12.9%的人使用过某种事后避孕方法,其中有事后3天内使用者占82.0%。92.6%的人赞成开展EC教育。73.7%的人认为,应在未婚青少年中开展EC教育。80.7%的人认为,在本单位进行EC教育是可行的。应答者认为,最易的接受的EC教育形式依次为:阅读材料(40.4%),录相(20.6%)和讲课(15.7%)。认为EC的最可靠的信息来源 相似文献
45.
免疫系统可识别、抵抗病原微生物及清除体内异常分裂的细胞,平衡的免疫系统对维持正常的机体反应活动至关重要。人体内的多种细胞都可参与维持免疫稳态,其中辅助性T淋巴细胞17(Th17)和调节性T淋巴细胞(Treg)发挥着重要作用,失衡的免疫系统可致多种免疫性疾病的发生。Th17/Treg细胞平衡受细胞因子、代谢、肠道微生态及翻译后修饰等多种机制调控,该文通过总结相关机制为免疫性疾病治疗提供新思路和策略。 相似文献
46.
Image-directed percutaneous biopsies with a biopsy gun 总被引:3,自引:0,他引:3
Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method. 相似文献
47.
Udaya DeSilva Laura Elnitski Jacquelyn R Idol Johannah L Doyle Weiniu Gan James W Thomas Scott Schwartz Nicole L Dietrich Stephen M Beckstrom-Sternberg Jennifer C McDowell Robert W Blakesley Gerard G Bouffard Pamela J Thomas Jeffrey W Touchman Webb Miller Eric D Green 《Genome research》2002,12(1):3-15
Williams syndrome is a complex developmental disorder that results from the heterozygous deletion of a approximately 1.6-Mb segment of human chromosome 7q11.23. These deletions are mediated by large (approximately 300 kb) duplicated blocks of DNA of near-identical sequence. Previously, we showed that the orthologous region of the mouse genome is devoid of such duplicated segments. Here, we extend our studies to include the generation of approximately 3.3 Mb of genomic sequence from the mouse Williams syndrome region, of which just over 1.4 Mb is finished to high accuracy. Comparative analyses of the mouse and human sequences within and immediately flanking the interval commonly deleted in Williams syndrome have facilitated the identification of nine previously unreported genes, provided detailed sequence-based information regarding 30 genes residing in the region, and revealed a number of potentially interesting conserved noncoding sequences. Finally, to facilitate comparative sequence analysis, we implemented several enhancements to the program, including the addition of links from annotated features within a generated percent-identity plot to specific records in public databases. Taken together, the results reported here provide an important comparative sequence resource that should catalyze additional studies of Williams syndrome, including those that aim to characterize genes within the commonly deleted interval and to develop mouse models of the disorder. 相似文献
48.
Gamma delta T cells in rhesus monkeys and their response to simian immunodeficiency virus (SIV) infection. 总被引:1,自引:0,他引:1 下载免费PDF全文
The principal cause of IL-2 deficiency, a common feature of both murine lupus and human SLE, remains obscure. Recent studies of our own as well as others have shown that dehydroepiandrosterone (DHEA), an intermediate compound in testosterone synthesis, significantly up-regulates IL-2 production of T cells, and that administration of exogenous DHEA or IL-2 via a vaccinia construct to murine lupus dramatically reverses their clinical autoimmune diseases. Thus, we have examined serum levels of DHEA in patients with SLE to test whether abnormal DHEA activity is associated with IL-2 deficiency of the patients. We found that nearly all of the patients examined have very low levels of serum DHEA. The decreased DHEA levels were not simply a reflection of a long term corticosteroid treatment which may cause adrenal atrophy, since serum samples drawn at the onset of disease, which are devoid of corticosteroid treatment, also contained low levels of DHEA. In addition, exogenous DHEA restored impaired IL-2 production of T cells from patients with SLE in vitro. These results indicate that defects of IL-2 synthesis of patients with SLE are at least in part due to the low DHEA activity in the serum. 相似文献
49.
为解决细胞内抗原应用免疫金银法染色时背景过重的问题,建立了甘氨酸二次阻断的处理方法,效果较好。 相似文献
50.
An affinity chromatography technique was utilized to isolate and purify the receptors of Escherichia coli K88ac(+) fimbriae from the mucus of the small intestines of newborn piglets. Purified K88ac+ fimbriae were covalently immobilized onto a beaded agarose matrix (Sepharose 4B). The immobilized fimbriae were used for the affinity purification of the K88ac+ receptors. Only two major proteins were tightly and specifically bound to the immobilized fimbriae after the column containing bound receptor was washed exhaustively with a buffer containing a high concentration of salt and a detergent. The receptors were eluted as a single component at a low pH. The isolated proteins were then subjected to enzyme-linked immunosorbent assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western blot (immunoblot) analyses. The two proteins were of high purity, were responsible for nearly all of the fimbrial binding capacity of the crude mucus, and had molecular masses of 26 and 41 kDa. The method for isolation of E. coli binding proteins is simple and yields purified intestinal receptors in a single chromatographic run. The intestinal mucus of different piglets has different proportions of the two receptor proteins. 相似文献