全文获取类型
收费全文 | 5505篇 |
免费 | 652篇 |
国内免费 | 189篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 57篇 |
妇产科学 | 8篇 |
基础医学 | 498篇 |
口腔科学 | 8篇 |
临床医学 | 299篇 |
内科学 | 464篇 |
皮肤病学 | 14篇 |
神经病学 | 41篇 |
特种医学 | 136篇 |
外科学 | 308篇 |
综合类 | 1648篇 |
预防医学 | 94篇 |
眼科学 | 5篇 |
药学 | 333篇 |
6篇 | |
中国医学 | 2271篇 |
肿瘤学 | 152篇 |
出版年
2024年 | 22篇 |
2023年 | 89篇 |
2022年 | 209篇 |
2021年 | 314篇 |
2020年 | 316篇 |
2019年 | 177篇 |
2018年 | 150篇 |
2017年 | 258篇 |
2016年 | 266篇 |
2015年 | 204篇 |
2014年 | 441篇 |
2013年 | 325篇 |
2012年 | 380篇 |
2011年 | 391篇 |
2010年 | 296篇 |
2009年 | 223篇 |
2008年 | 215篇 |
2007年 | 201篇 |
2006年 | 193篇 |
2005年 | 169篇 |
2004年 | 138篇 |
2003年 | 130篇 |
2002年 | 126篇 |
2001年 | 132篇 |
2000年 | 100篇 |
1999年 | 100篇 |
1998年 | 62篇 |
1997年 | 53篇 |
1996年 | 50篇 |
1995年 | 67篇 |
1994年 | 58篇 |
1993年 | 39篇 |
1992年 | 31篇 |
1991年 | 32篇 |
1990年 | 41篇 |
1989年 | 28篇 |
1988年 | 29篇 |
1987年 | 32篇 |
1986年 | 23篇 |
1985年 | 38篇 |
1984年 | 35篇 |
1983年 | 22篇 |
1982年 | 28篇 |
1981年 | 27篇 |
1980年 | 11篇 |
1979年 | 17篇 |
1978年 | 17篇 |
1977年 | 14篇 |
1976年 | 14篇 |
1974年 | 5篇 |
排序方式: 共有6346条查询结果,搜索用时 15 毫秒
21.
Margaret J. Tango Evelyn Safaris Margarita Romanella Atousa Aminian Marina Katerelos Christine Somerwille RIek G. Tearle Martin J. Pearse Anthony J.E d'Apice 《Xenotransplantation》1997,4(1):25-33
Abstract: Transgenic expression of the human complement regulatory molecule CD59 in mice and genetic deletion of the major xenoantigen galactose α 1,3 galactose (Gal KO) each resulted in partial protection of spleen cells from lysis by human serum. These protective effects were additive when the two genetic modifications were combined. However, when the effects of these genetic modifications were examined in an ex vivo model in which mouse hearts were perfused with human plasma, it was Gal KO which was the modification which determined protection. CD59 expression alone was not protective and CD59 expression in combination with Gal knockout did not result in a significant additional increase in protection over and above that provided by Gal knockout alone. The likely explanation for this discrepancy between the in vitro and ex vivo data is that the H2-Kb promoter used to drive CD59 expression results I in substantially less expression on endothelium than on spleen cells. 相似文献
22.
Ana Sánchez-Romero Israel Oliver David Costa Albina Orduña Javier Lacueva Francisco Pérez-Vicente Antonio Arroyo Rafael Calpena 《Clinical & translational oncology》2006,8(4):294-295
Lung cancer is the most prevalent malignancy in western countries and most of the patients present at advanced stages, but
single splenic metastasis is exceptional instead. We report on a case of a seventy-three-year old male presenting with non-hemoptoic
productive cough, constitutional syndrome and pain in the left lower quadrant. Physical examination and complementary radiological
and hystologycal procedures revealed the presence of an adenocarcinoma of the left lung with probable splenic metastasis.
The patient underwent splenectomy, which confirmed the diagnose of splenic metastasis of lung adenocarcinoma and, secondly,
lung resection was performed. Topics about lung cancer metastasis are discussed. 相似文献
23.
24.
本文报告用~3H-TdR掺入法测定本室的NC系正常裸小鼠和荷人脑胶质瘤裸小鼠(NHG-1)的脾淋巴细胞转化功能。结果提示:正常的纯合子(nu/nu)T细胞缺乏,B细胞功能均正常;杂合子(nu/ )的T和B细胞功能均正常;荷瘤鼠(NHG-1,30代)除了T细胞缺乏,B细胞功能亦受到抑制。 相似文献
25.
白术茯苓汤及其配伍对脾虚大鼠胃肠激素的影响 总被引:3,自引:0,他引:3
目的:探讨益气健脾方剂治疗脾虚证的配伍规律。方法:采用苦寒泻下法复制大鼠脾虚模型,运用放射免疫分析法(RIA)检测白术茯苓汤及其与补气药。行气药及除湿药的不同配伍对脾虚大鼠胃泌素(GAS)、胃动素(MTL)及血管活性肠肽(VIP)的含量影响。结果:与正常对照组比较,脾虚模型大鼠GAS、MTL降低(P<0.01),VIP升高(P<0.01);与自然恢复组比较,各治疗组以上部分或全部指标均有不同程度的改善,其中,以综合配伍组改善作用最优。结论:白术茯苓汤的脾虚大鼠胃肠激素的紊乱的某些指标,有一定的改善作用,综合配合组以上指标的改善,优于白术茯苓汤组及其余各配伍组,说明中医关于复方配伍的理论与实践,有其科学价值。 相似文献
26.
本文报告1例脾萎缩伴暴发性肺炎球菌败血症、脑膜炎、播散性血管内凝血(DIC)及华-弗氏综合征。血培养分离出肺炎球菌。尸体解剖发现脾萎缩、双侧肾上腺出血及坏死。显微镜检查有肺炎、脑膜炎、DIC及华-弗氏综合征的组织学证据。对本病的发病机理和防治进行讨论 相似文献
27.
Y. Kannan R. H. Stead C. H. Goldsmith J. Bienenstock 《Journal of neuroscience research》1994,37(3):374-383
Induction of neurite outgrowth from superior cervical ganglia (SCG) by rat lymphoid tissues was studied using a tissue culture model. Neonatal rat SCG were cultured with 6–12-week-old rat thymus, spleen, or mesenteric lymph node (MLN) explants in a Martrigel layer, in defined culture medium without exogenous nerve growth factor (NGF). SCG were also co-cultured with neonatal rat heart (as positive control) or spinal cord (SC; as negative control). To determine whether inflammation affects the ability of lymphoid tissues to induce neurite outgrowth, we also examined MLN at various times after infecting rats with Nippostrongylus brasiliensis (Nb-MLN). In one series of experiments, a single lymphoid tissue explant was surrounded by four SCG at a distance of 1 mm. The extent of neurite outgrowth was determinded by counting the number of neurites 0.5 mm away from each ganglion at several time points. Adult thymus and, to a lesser extent, spleen had strong stimulatory effects on neurite outgrowth from SCG after 12 hr or more in culture. For thymus tissue, this was similar to the positive control heart explants. MLN from normal rats had minimal effect on neurite outgrowth; however, Nb-MLN showed a time-dependent enhancement of the neurite outgrowth, maximal at 3 weeks after infection. The relative efficacy of neurite outgrowth induction (heart ≥ thymus ≥ Nb-MLN ≥ spleen ≥ MLN ≥ SC) was confirmed in a second series of experiments where one SCG was surrounded by three different tissue explants. We then examined the role of 2.5S NGF, a well-known trophic factor for sympathetic nerves, in the lymphoid tissue-induced neurite outgrowth. Anti-NGF treatment of co-cultures of SCG and heart almost completely blocked the neurite outgrowth. Anti-NGF also significantly inhibited thymus- and spleen-induced neurite outgrowth, but not as effectively as heart-induced neuritogenesis (93,80, and 77% inhibition at 24 hr; 86,70, and 68% inhibition at 48 hr for heart, thymus, and spleen, respectively). On the other hand, anti-NGF inhibited only 8% of neurite outgrowth induced by 3-week post-infection Nb-MLN at 24 hr, and 41% at 48 hr. These data show that several adult rat lymphoid tissues exert neurotrophic/tropic effects. The predominant growth factor in thymus and spleen is NGF, while Nb-MLN produces factor(s) which is (are) immunologically distinguishable from NGF. These neurotrophic/tropic factors are produced during the reactive lymphoid hyperplasia that forms part of the inflammatory response against the nematode, N. brasiliensis. This suggests the possibility that cytokines produced by lymphocytes or other inflammatory cells may stimulate sympathetic neurite outgrowth in vivo. © 1994 Wiley-Liss, Inc. 相似文献
28.
29.
Anane Aidoo Lascelles E. Lyn-Cook Shelly Lensing Wayne Wamer 《Environmental and molecular mutagenesis》1994,24(3):220-228
Recent reports suggest that ascorbic acid (vitamin C) inhibits tumorigenesis as well as exerts a protective effect against mutagenesis in vitro; however, there is no information on its ability to affect gene mutations induced in vivo. In this study, we have investigated the antimutagenic effects of ascorbic acid on the frequency of 6-thioguanine-resistant (6-TGr) T-lymphocytes produced in Fischer 344 rats dosed with the direct-acting alkylating agent, N-ethyl-N-nitrosourea (ENU). The freqeuncy of 6-TGr T-lymphocytes from the spleen measured five weeks after ENU treatment indicated that ENU produced a substantial mutagenic response. Pretreatment and/or post-treatment of rats with ascorbic acid administered in the drinking water appeared to inhibit the response, but the inhibition was statistically significant only when data from the various dosing schedules were pooled. In addition, there was no clear dose-dependency to the inhibitory effect of ascorbic acid. To further evaluate the time effects of the vitamin supplement on ENU mutagenicity, rats were exposed to the mutagen together with ascorbic acid, which was given continuously for the entire duration of the experiment. At specific times after ENU treatment, the frequency of 6-TGr T-cells was determined in lymphocytes isolated from the spleen and the thymus. Time-dependent increases in the frequency of 6-TGr T-cells were observed with ENU treatment; ascorbic acid significantly reduced the ENU-mediated mutagenic responses, most dramatically in the spleen at weeks 6 and 8 (P < 0.0001), and to a lesser extent in the thymus (P < 0.01 at week 6 and P < 0.006 at week 8). Our data suggest that ascorbic acid intake affects the in vivo mutagenicity of ENU, a direct-acting mutagen/carcinogen, and that the reported inhibitory effects of the antioxidant on carcinogenesis may be partially mediated by its effects on mutagenesis. Although it is difficult to extrapolate from rodent studies to humans, the results presented suggest an explanation for epidemiological data that link vitamin C ingestion with decreased cancer risk. © 1994 Wiley-Liss, Inc. 相似文献
30.
Generalizedlymphangiomatosisisaveryraredis-easethatischaracterizedbydisseminateddilationandproliferationoflymphaticsinvolvingbone,vis-cera,etc.Thepatients'presentationsarevarious,andchyluseffusionisamoreoftenpresentingsymp-tom.Herein,wediscussedapatientwhopresentedwithaninguinalmass.Themanifestationwasunusualfortheraredisease.Alsowereviewedrecentlitera-tureaboutthedisease.CASEREPORTA30?year?oldwomanpresentedtoourhospitalwithachiefcomplaintof“arecurrentmovablemassintheleftinguinalcanalfor… 相似文献