首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23517篇
  免费   2346篇
  国内免费   812篇
耳鼻咽喉   166篇
儿科学   598篇
妇产科学   332篇
基础医学   3483篇
口腔科学   413篇
临床医学   1671篇
内科学   5050篇
皮肤病学   410篇
神经病学   1822篇
特种医学   412篇
外国民族医学   4篇
外科学   2193篇
综合类   2952篇
现状与发展   5篇
一般理论   2篇
预防医学   1276篇
眼科学   264篇
药学   2925篇
  2篇
中国医学   741篇
肿瘤学   1954篇
  2024年   48篇
  2023年   592篇
  2022年   1280篇
  2021年   1168篇
  2020年   983篇
  2019年   1294篇
  2018年   1163篇
  2017年   1105篇
  2016年   956篇
  2015年   1062篇
  2014年   1531篇
  2013年   1439篇
  2012年   1401篇
  2011年   1625篇
  2010年   1460篇
  2009年   1190篇
  2008年   1142篇
  2007年   995篇
  2006年   812篇
  2005年   739篇
  2004年   668篇
  2003年   490篇
  2002年   348篇
  2001年   300篇
  2000年   339篇
  1999年   271篇
  1998年   201篇
  1997年   159篇
  1996年   155篇
  1995年   129篇
  1994年   90篇
  1993年   89篇
  1992年   71篇
  1991年   76篇
  1990年   62篇
  1989年   54篇
  1988年   45篇
  1987年   39篇
  1985年   123篇
  1984年   126篇
  1983年   112篇
  1982年   120篇
  1981年   105篇
  1980年   87篇
  1979年   110篇
  1978年   64篇
  1977年   53篇
  1976年   44篇
  1975年   40篇
  1973年   34篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
目的 :探讨层粘连蛋白 (LN)、基质金属蛋白酶 9(MMP 9)在卵巢粘液性肿瘤中的表达以及与临床病理因素和预后的关系。方法 :应用免疫组织化学方法检测 43例卵巢粘液性肿瘤LN、MMP 9的表达情况。结果 :LN、MMP 9的表达 ,在卵巢粘液性肿瘤从良性、交界性到恶性发展中 ,LN的表达级别和MMP 9的表达阳性率逐渐增高 ;LN的表达程度与卵巢粘液性囊腺癌的组织学分级有关 (P =0 0 0 0 ) ;MMP 9的表达与卵巢粘液性囊腺癌的组织学分级 (P =0 0 48)、FIGO分期 (P =0 0 47)、术后复发和死亡 (P =0 0 30 )有关。在卵巢粘液性囊腺癌中 ,LN的表达程度在MMP 9阳性组与MMP 9阴性组之间差异有显著性 (P =0 0 0 8) ,并呈正相关。结论 :LN、MMP 9在卵巢粘液性肿瘤的浸润转移中起重要作用 ,是卵巢粘液性肿瘤的恶性指标之一 ,可望作为交界性粘液性囊腺瘤及粘液性囊腺癌的诊断和分级的客观指标 ;MMP 9可协助临床估计预后。  相似文献   
72.
73.
The degradation of the basement membrane by matrix-metalloproteinase(MMP) and serine protease is a critical pointin tumor invasion and metastasis. We measured theactivity of MMP-9 from 28 normal, 12 benignand 126 breast cancer tissues using gelatin zymographywith an image analysis system. ProMMP-9 was expressedin 17.5% of the cancer patients compared to2.5% in 40 non-cancerous tissues (p=0.014).The mature form of MMP-9 (82 kD) wasexpressed only in T2–T4 stages. During the earlyphase of breast cancer (DCIS and T1 stage)progression, only production of proMMP-9 increased. However, asthe cancer grew or invaded skin (T2–T4), orwith lymphovascular permeation, both production and activation ofMMP-9 increased. In conclusion, proMMP-9 production was themain cause of increased MMP-9 activity during theearly phase, while both production and activation increasedin the late phase of breast cancer.  相似文献   
74.
Persistent hyperinsulinemic hypoglycaemia of infancy (PHHI) is the most frequent cause of hypoglycaemia in infancy. Clinical presentation is heterogeneous, with variable onset of hypoglycaemia and response to diazoxide, and presence of sporadic or familial forms. Underlying histopathological lesions can be focal or diffuse. Focal lesions are characterised by focal hyperplasia of pancreatic islet-like cells, whereas diffuse lesions implicate the whole pancreas. The distinction between the two forms is important because surgical treatment and genetic counselling are radically different. Focal lesions correspond to somatic defects which are totally cured by limited pancreatic resection, whereas diffuse lesions require a subtotal pancreatectomy exposing to high risk of diabetes mellitus. Diffuse lesions are due to functional abnormalities involving several genes and different transmission forms. Recessively inherited PHHI have been attributed to homozygote mutations for the beta-cell sulfonylurea receptor (SUR1) or the inward-rectifying potassium-channel (Kir6.2) genes. Dominantly inherited PHHI can implicate the glucokinase gene, particularly when PHHI is associated with diabetes, the glutamate dehydrogenase gene when hyperammonaemia is associated, or another locus.  相似文献   
75.
To investigate the mechanism of chronic cell death following postischemic hypothermia, the change of N-methyl- -aspartate receptor (NMDAR) were examined by immunohistochemistry of NMDAR1 and long-term potentiation (LTP) in the CA1 subfield of the gerbil hippocampus. At 1 week following postischemic hypothermia (32°C×4 h), all CA1 neurons survived; however, immunoreactivity of NMDAR1 increased in neuronal perikarya whereas decreased in dendrites in the CA1 neurons. The abnormality was still observed in remaining CA1 neurons at 1 month after hypothermia. LTP was also significantly depressed at 1 week after hypothermia. These results suggest that some abnormalities in the glutamate receptor may be caused by ischemia; such abnormality would persist in spite of hypothermia treatment, resulting in the depression of LTP.  相似文献   
76.
The ventrolateral periaqueductal gray (PAG) and pontine reticular formation (PRF) are implicated in the neuronal network for audiogenic seizures (AGS). The AGS of genetically epilepsy-prone rats (GEPR-9s) culminate in tonic hindlimb extension (TE), and elevated acoustically evoked neuronal firing and burst firing, immediately preceding TE, have been observed in PAG and PRF. This study examined changes in PAG and PRF neuronal firing and behavior in GEPR-9s, following phenytoin administration. Recordings involved 16 PAG and nine PRF neurons in GEPR-9s. Phenytoin in doses (mean, 6. 3 mg/kg) that suppressed TE selectively did not consistently alter PAG neuronal firing. However, these doses of phenytoin resulted in significant (51.6% of control) suppression of PRF neuronal firing. Doses of phenytoin (mean, 8.3 mg/kg), which completely blocked AGS, significantly reduced PAG neuronal firing (64.6% of control), and more greatly suppressed PRF firing (25.8% of control). These results are consistent with a critical role for PRF neurons in generation of TE not evident for PAG. The suppression of PAG and PRF neuronal firing induced by phenytoin with complete seizure blockade is consistent with vital roles for both structures in the seizure network. The differential effects of phenytoin on structures requisite to the seizure network indicate that this experimental approach may be able to identify the most sensitive therapeutic target for anticonvulsant drugs, which could be critical to pharmacological suppression of specific seizure behaviors manifest in various types of convulsions, potentially including human epilepsy.  相似文献   
77.
论述了颈部的局部解剖结构及常用穴位,以人迎穴为例,对针刺颈部穴位的刺法和注意事项进行阐述.  相似文献   
78.
宋艳  龚蕊  杨波  王磊  张玲 《西部医学》2019,31(12):1820-1825
目的 探讨汉黄芩苷(Wog)对缺氧复氧诱导H9c2心肌细胞损伤及P38和ERK1/2表达的影响。方法 培养心肌细胞H9c2构建缺氧复氧模型(A/R),给予Wog低、中、高剂量(12.5、25、50 μM)处理24h,采用CCK8检测48 h后细胞活力,Hochest染色检测细胞凋亡,ELISA检测细胞上清液中心肌损伤标记物[肌酸激酶(CK),肌酸激酶同工酶(CK MB)、肌红蛋白(Mb)]和炎性细胞因子[白介素6(IL-6)、白介素1β(IL-1β)和诱导型一氧化氮合酶(iNOS)]的含量,生化试剂盒检测氧化应激指标[超氧化物歧化酶(SOD)、丙二醛(MDA)及乳酸脱氢酶(LDH)]的含量,Western blot检测相关蛋白[B淋巴细胞瘤-2基因(Bcl-2)、Bcl-2相关x蛋白(Bax)、半胱氨酸天冬氨酸蛋白酶3(Caspase-3)、Caspase-9]、丝裂原活化蛋白激酶P38及细胞外调节激酶(ERK1/2)的表达。 结果 低、中、高剂量Wog处理缺氧复氧模型细胞H9c2,细胞存活率、Bcl-2及SOD的表达显著升高,凋亡率、Bax、Caspase-3、Caspase-9、CK、CK-MB、Mb、IL-6、IL-1β、iNOS、MDA、LDH、P38及ERK1/2的表达显著降低(均P<0.05)。 结论 汉黄芩苷可通过改善炎症反应和氧化应激损伤,减少心肌细胞的凋亡,对缺氧复氧诱导H9c2心肌细胞损伤具有一定的保护作用,可能与下调P38、ERK1/2磷酸化有关。  相似文献   
79.
MMPs与慢性子宫内膜炎及不孕症的研究   总被引:2,自引:0,他引:2  
基质金属蛋白酶是一族依赖锌离子而降解各种细胞外基质的蛋白酶.基质金属蛋白酶的组织特异性抑制物是一组多功能基因家族,它们能特异性地抑制基质金属蛋白酶.基质金属蛋白酶-2和基质金属蛋白酶-9是最典型的代表,在子宫内膜均有表达.基质金属蛋白酶的组织特异性抑制物-1是基质金属蛋白酶-9的特异性抑制因子;基质金属蛋白酶的组织特异性抑制物-2是基质金属蛋白酶-2的天然抑制物.在胚胎植入等过程中,基质金属蛋白酶发挥着重要的作用.该文就基质金属蛋白酶-2和基质金属蛋白酶-9及其抑制物与慢性子宫内膜炎和不孕症的关系进行综述.  相似文献   
80.
The syndrome of Leser‐Trélat (LT) is a rare paraneoplastic syndrome. However, patients presenting with the sign of Leser‐Trélat should be considered to harbor an occult malignancy or a progressive tumor disease until “proven” otherwise. Herein, we present two cases of non‐small‐cell lung carcinoma associated with LT syndrome.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号