全文获取类型
收费全文 | 24623篇 |
免费 | 2047篇 |
国内免费 | 617篇 |
专业分类
耳鼻咽喉 | 137篇 |
儿科学 | 563篇 |
妇产科学 | 343篇 |
基础医学 | 2229篇 |
口腔科学 | 396篇 |
临床医学 | 4235篇 |
内科学 | 5599篇 |
皮肤病学 | 170篇 |
神经病学 | 1822篇 |
特种医学 | 1403篇 |
外国民族医学 | 3篇 |
外科学 | 2502篇 |
综合类 | 2855篇 |
现状与发展 | 4篇 |
预防医学 | 750篇 |
眼科学 | 205篇 |
药学 | 2183篇 |
12篇 | |
中国医学 | 666篇 |
肿瘤学 | 1210篇 |
出版年
2024年 | 43篇 |
2023年 | 400篇 |
2022年 | 600篇 |
2021年 | 1042篇 |
2020年 | 1057篇 |
2019年 | 993篇 |
2018年 | 1007篇 |
2017年 | 894篇 |
2016年 | 835篇 |
2015年 | 843篇 |
2014年 | 1406篇 |
2013年 | 1726篇 |
2012年 | 1204篇 |
2011年 | 1296篇 |
2010年 | 1040篇 |
2009年 | 1090篇 |
2008年 | 991篇 |
2007年 | 1069篇 |
2006年 | 882篇 |
2005年 | 813篇 |
2004年 | 687篇 |
2003年 | 621篇 |
2002年 | 516篇 |
2001年 | 509篇 |
2000年 | 447篇 |
1999年 | 411篇 |
1998年 | 406篇 |
1997年 | 373篇 |
1996年 | 335篇 |
1995年 | 339篇 |
1994年 | 324篇 |
1993年 | 278篇 |
1992年 | 260篇 |
1991年 | 236篇 |
1990年 | 236篇 |
1989年 | 205篇 |
1988年 | 221篇 |
1987年 | 168篇 |
1986年 | 153篇 |
1985年 | 216篇 |
1984年 | 207篇 |
1983年 | 150篇 |
1982年 | 181篇 |
1981年 | 132篇 |
1980年 | 91篇 |
1979年 | 71篇 |
1978年 | 62篇 |
1977年 | 53篇 |
1976年 | 52篇 |
1975年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
SUNG-GOO CHANG CHUL-SOO KIM SEUNG HYUN JEON YOUN-WHA KIM BO YOUL CHOI 《International journal of urology》2006,13(2):122-126
AIM: To evaluate the cause of elevated prostate-specific antigen (PSA) in patients with transrectal needle biopsy negative for prostate cancer. METHODS: Serum PSA concentration, prostate volume, and pathologic findings were examined in 223 patients with negative biopsy for prostate cancer. The degree of prostate inflammation was determined by the extent and degree of inflammation shown by biopsy specimens and is expressed as an inflammation score (range: 0-36). RESULTS: A significant correlation was found between PSA concentration and prostate total volume (P=0.0001). Prostate chronic inflammation showed no correlation with PSA concentration (P=0.485, F=0.488). After allocating patients to normal PSA (4 ng/mL) groups, we found that serum PSA concentrations in both groups were predominantly affected by prostate total volume. CONCLUSIONS: An increase in prostate volume appears to be the major contributor to a high serum PSA concentration in patients with negative biopsy for prostate cancer. However, in contrast to previous reports, there was no correlation between the degree of prostate chronic inflammation and serum PSA concentrations. 相似文献
62.
The effect of a two day fast on maternal plasma volume and plasma protein concentration was explored in pregnant rats. Fasting between days 17 and 19 of gestation prevented the rise in plasma volume observed in ad libitum fed rats. Plasma protein concentration declined between day 17 and day 19 in both fasted and not fasted rats. Placental weight was not reduced by fasting during this stage of gestation. Fetal weight in the fasted group was 91% of the fetal weight of the ad libitum fed group. These results show that acute undernutrition, like longer term food or protein restriction, can prevent adequate plasma volume expansion and slow fetal growth. 相似文献
63.
应用鸡卵清蛋白致敏和刺激小鼠复制过敏性气道炎症反应模型研究血小板激活因子选择性拮抗剂YM-264对抗原引起气道嗜酸性粒细胞(EOS)浸润的影响。结果发现,正常小鼠支气管肺泡灌洗液(BALF)中未见到EOS;致敏小鼠给予抗原多次反复吸入刺激后,BALF中EOS急剧增多。在YM-264治疗各组中,YM-264的不同剂量分别导致EOS数下降27.0%、48.2%及67.9%。还发现YM-264抑制EOS对气道的浸润伴随着白细胞介素(IL)-5水平的明显下降。提示YM-264通过抑制IL-5的产生从而抑制了EOS在气道的聚集。 相似文献
64.
茶色素对冠心病及高血压病病人血小板功能的影响 总被引:1,自引:0,他引:1
目的:探索茶色素对冠心病、高血压病病人血小板功能的影响。方法:冠心病病人36例(男性21例,女性15例;年龄64±s4a);高血压病病人30例(男性18例,女性12例;年龄58±8a)。采用茶色素250mg,po,tid,30d为一个疗程。结果:治疗后TXB2下降,6-keto-PGP1α上升,TXB2/6-keto-PGF1α比值下降(P<0.01或P<0.05),GMP-140下降(P<0.05),PagT,PadT下降(P<0.05)。结论:茶色素具有降低血小板表面活性作用,抑制血小板聚集和粘附,抗血栓形成,改善微循环,对冠心病和高血压病病人起到积极的防治作用。 相似文献
65.
单波长荧光分光光度计测定细胞内Ca^2+浓度的方法探索 总被引:2,自引:1,他引:1
在使用单波长荧光分光光度计测定细胞内游离钙浓度时,通过快速(4~6s)手动转换激发波长(EX),分别测定EX340和380nm时的荧光强度变化,并计算出340nm与380nm时的荧光强度比率(R),然后也采用双波长荧光分光光度计测定细胞内Ca2+浓度的计算公式计算细胞内游离钙浓度。结果显示单波长荧光分光光度计按比例法测得的细胞内游离Ca2+浓度与使用双波长荧光分光光度计测得的结果相似。 相似文献
66.
R. Berkels A. Bertsch T. Zuther S. Dhein K. Stockklauser P. Rsen R. Rsen 《European journal of haematology》1997,58(5):307-313
Abstract: We tried to characterize the porcine platelet nitric oxide (NO) synthase and its L-arginine (L-arg)/NO metabolism. Using RT-PCR we could show a constitutive endothelial NOS (ecNOS) and an inducible NOS (iNOS) similar mRNA in platelets. The NOS protein could be evidenced by an ecNOS specific antibody which also bound in platelets. This finding could be confirmed by Western blot showing an ecNOS in the membrane but not the cytosolic fraction; iNOS protein could not be detected. Using NADPH-diaphorase staining we could show NO synthase in preactivated platelets but not in resting platelets, indicating that the platelet NOS may be activated during platelet activation/aggregation. Porcine L-arg plasma levels (9.31 × 10–5 mol/l ± 10%) could be shown to be in the same range as human plasma levels. Moreover, we could show that the NO precursor L-arg and hydroxy-L-arginine (OHarg) concentration dependently inhibited collagen induced platelet aggregation. Summarizing these results confirm the existence of and further characterize porcine platelet NO synthases. 相似文献
67.
Masaki Hata Akinori Nango Hisateru Niki Yoshifumi Hayafune Atsushi Kato 《Journal of orthopaedic science》1997,2(1):3-9
To elucidate the growth of the tarsal bones in congenital clubfoot, relative to the growth of these bones in the unaffected feet and compared to growth in the feet of normal volunteers, we used a computed tomography (CT) scanner to measure the volume of all tarsal bones. The subjects of the study were 10 adults (7 men and 3 women) with unilateral congenital clubfoot (average age 20 years and 1 month). As controls, we examined 11 healthy volunteers. We calculated the ratio of the volume of each tarsal bone to the total bone volume and the ratio of the volume of each tarsal bone in clubfoot to the corresponding bone in the unaffected foot. The volume ratio of each tarsal bone was compared between clubfeet and unaffected feet because the differences of each tarsal bone ratio between the normal foot group and unaffected foot group were not significant. In the clubfeet (n=10), the talus and the medial cuneiform bones were smaller than those in the unaffected feet (n=10) but the cuboid bone was larger. The growth of the navicular did not differ from as that in unaffected feet. Our results suggested hypoplasia on the medial side of the foot in adult patients with congenital clubfoot. The 3 patients who had undergone medial release showed particularly marked hypoplasia of the medial side. In congenital clubfoot cases with severe deformities who had undergone wide soft-tissue release operations, there were clear growth suppressions in the talus and the medial cuneiform. We could not determine whether the cause of the growth suppression was the hypoplastic nature of tarsal bones themselves or the surgical obstacles to tarsal bone growth. 相似文献
68.
成人原发性肾病综合征血容量与肾素,醛固酮,心钠素的关系 总被引:2,自引:0,他引:2
探讨成人原发性肾病综合征(NS)血容量与肾素、醛固酮及心钠素的关系。方法 应用~(113)mInCl标记转铁蛋白稀释法测定血容量,放免法测定血浆激素水平。对水肿期NS28例、正常26例及其中NS缓解期随访18例进行检测。结果 (1)水肿期NS血容量与正常组无差别,血浆肾素活性(PRA)、血管紧张素Ⅱ(ATⅡ)、醛固酮(Ald)、心钠素(ANP)水平均较正常组高,白蛋白、各激素水平与血容量无显著相关;(2)缓解期与水肿期比较,总的血容量无差异,Ald、ANP显著降低,PRA、ATⅡ则无明显差异;(3)Ald与24小时尿排钠(UNaV)显著负相关。结论 Ald和ANP是NS钠排泄的主要调节因子。 相似文献
69.
Bo-Lennart Johansson Ulla Berg Ulla Freyschuss Kerstin Hall Staffan Troell 《Pediatric nephrology (Berlin, Germany)》1990,4(6):589-592
The influence of metabolic control (HbA1c), noradrenaline (NA) and insulin-like growth factors (IGF-I and IGF-II) on renal function and size was investigated in 11 insulin-dependent diabetes mellitus patients aged 11–17 years. Renal function was evaluated in terms of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). Renal size was determined as renal parenchymal volume (RPV) by ultrasonography. The patients' HbA1c values ranged from 8.2% to 12.9% (normal range 5.5–8.5%) and their GFR and ERPF were higher than normal. Their IGF-II values were higher, and NA and IGF-I levels were lower than those of healthy controls. Inverse correlations between NA and GFR (r=–0.66) and NA and ERPF (r=–0.63) were found. No correlation was found between serum IGF-I and renal functional parameters. The IGF-II values correlated with GFR and HbA1c (r=0.63,r=0.70 respectively). There were linear correlations between RPV and GFR, RPV and ERPF, HbA1c and GFR, and ERPF and RPV. Decreased NA concentrations and increased IGF-II values appear to be factors contributing to renal hyperfunction in these patients. 相似文献
70.
In rabbit platelet rich plasma (PRP), 5-hydroxytraptamine (5-HT,0.03~3μmol/L) induced decrease in light transmission (DLT) dose-de pendently with centralization, as revealed by electron microscopy. However, 5-HT did not induced platelet aggregation and release reaction. 5-HT-induced DLT was inhibited by methysergide (0.3~30μmol/L), indomethacin (0.3~10μmol/L) and PGE_1 (0.01~0.3μmol/L) in a dose-dependent manner, but not EGTA(0.3~3mmol/L). Collagen(Coll), arachidonic acid (AA), adenosine diphosphate (ADP) and a stable thromboxane A2 analoge(STA_2) also induced DLT before aggregation by themselves, which was also inhibited by PGE_1, but not inhibited by EGTA except for Coll However,Coll-, AA-, STA_2-and ADP-induced DLT were reduced by pretreatment of PRP with 5-HT dose-depen-dently. The duration of DLT by Coll and AA were decreased from 151.4±5.93 sec and 15(?)38±0.60sec to 45.44±4.04 sec and 9.00±1.25 sec respectively ((?)±s(?) P<0.01), but not by ADP and STA_2, 3μmol/L of ADP-and 0.3μmol/L of STA_2-induced aggregation which was not accompanied with release reaction were enhanced by 5-HT pretreatment, but in those (Coil 5μg/ml, AA 100~200μmol/L and STA_2 1~3 μmol/L) with release reaction, the amount of adenosine triphosphate(ATP)were suppressed significantly (P<0.001) by 5-HT pretreatment without the effect on the magnitude of aggregation, The mobilization of cytosolic free calcium concentration ([Ca~(2+)]i) was observed after 5-HT treatment in single washed platelet, the results indicated that the basic level of [Ca~(2+)] i was 64.78±3.24nmol/L and this level was increased dose-dependently and significantly at 30 sec after administration of 5-HT and the time of peak value of [Ca~(2+)] i was at 90~100 sec.The similar time courses of suppression of ATP released during aggregation, in cases of Coll(5μg/ml), AA (200μmol/L) and STA_2(3μmol/L), by 5-HT were also found in the present experiment. 相似文献