全文获取类型
收费全文 | 85785篇 |
免费 | 7256篇 |
国内免费 | 4436篇 |
专业分类
耳鼻咽喉 | 625篇 |
儿科学 | 3108篇 |
妇产科学 | 2301篇 |
基础医学 | 10594篇 |
口腔科学 | 2204篇 |
临床医学 | 6992篇 |
内科学 | 13295篇 |
皮肤病学 | 1323篇 |
神经病学 | 5475篇 |
特种医学 | 2349篇 |
外国民族医学 | 32篇 |
外科学 | 9094篇 |
综合类 | 14509篇 |
现状与发展 | 19篇 |
预防医学 | 3469篇 |
眼科学 | 3508篇 |
药学 | 8209篇 |
21篇 | |
中国医学 | 3424篇 |
肿瘤学 | 6926篇 |
出版年
2024年 | 123篇 |
2023年 | 932篇 |
2022年 | 1472篇 |
2021年 | 2666篇 |
2020年 | 2391篇 |
2019年 | 2302篇 |
2018年 | 2273篇 |
2017年 | 2604篇 |
2016年 | 2723篇 |
2015年 | 2966篇 |
2014年 | 5023篇 |
2013年 | 6131篇 |
2012年 | 4975篇 |
2011年 | 5626篇 |
2010年 | 4856篇 |
2009年 | 4760篇 |
2008年 | 4948篇 |
2007年 | 5152篇 |
2006年 | 4640篇 |
2005年 | 4274篇 |
2004年 | 3698篇 |
2003年 | 3220篇 |
2002年 | 2685篇 |
2001年 | 2280篇 |
2000年 | 1997篇 |
1999年 | 1598篇 |
1998年 | 1380篇 |
1997年 | 1211篇 |
1996年 | 1147篇 |
1995年 | 945篇 |
1994年 | 833篇 |
1993年 | 713篇 |
1992年 | 630篇 |
1991年 | 559篇 |
1990年 | 478篇 |
1989年 | 396篇 |
1988年 | 297篇 |
1987年 | 290篇 |
1986年 | 264篇 |
1985年 | 366篇 |
1984年 | 293篇 |
1983年 | 197篇 |
1982年 | 248篇 |
1981年 | 219篇 |
1980年 | 151篇 |
1979年 | 113篇 |
1978年 | 102篇 |
1977年 | 78篇 |
1976年 | 68篇 |
1975年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 216 毫秒
991.
Kiyoshi Imaizumi Kenji Kurosawa Yoshio Makita Mitsuo Masuno Yoshikazu Kuroki 《Clinical genetics》1994,45(1):40-43
A 5-year-old boy, who had pre- and postnatal growth retardation, delayed motor development, cutis laxa, delayed closure of large fontanels, congenital hip dislocation and characteristic facies, is described. Disorders with cutis laxa are now divided into five types. The patient had clinical manifestations very similar to those of cutis laxa with bone dystrophy (type II autosomal recessive cutis laxa). Eighteen patients have been reported, the ratio of males to females being 5 to 14. This is the fifth case of this disorder occurring in a male, which provides further evidence for autosomal recessive inheritance. 相似文献
992.
In isolated, perfused mesenteric vascular beds from female rats, it was assessed whether the constrictor response to cirazoline, an alpha(1)-adrenergic agonist, or acetylcholine (ACh)-induced relaxation was altered by oestrous cycle or pregnancy and the ability of nitric oxide (NO), prostanoids and endothelium-derived hyperpolarizing factor (EDHF) to modulate these responses. Mesenteries, removed from female rats on each oestrous cycle day and gestation day 16, were perfused with physiological salt solution. Tone was induced with cirazoline (1 micromol/l), and concentration-response curves to ACh generated. Responsiveness to ACh was tested in the presence of N(omega)-nitro-L-arginine (L-NA), ibuprofen (IBU) and tetrabutylammonium (TBA), to inhibit nitric oxide synthase (NOS), cyclo-oxygenase and K(+) channels respectively. Cirazoline-induced tone was smaller in pro-oestrous and pregnant groups, but the increase in tone to L-NA was larger in pregnant compared with oestrous and dioestrous groups. Control responses to ACh were not different, but L-NA attenuated the response in virgin groups only. IBU did not affect the ACh response, but TBA attenuated it in all groups. When TBA was introduced first, ACh-induced dilatation was significantly reduced and not altered by L-NA addition. These results suggest that in the mesenteric vascular bed from cycling and pregnant rats, EDHF is the major mediator of ACh-induced dilatation and NOS may be up-regulated in pregnant and pro-oestrous rats. 相似文献
993.
Hugues JN Soussis J Calderon I Balasch J Anderson RA Romeu A;Recombinant LH Study Group 《Human reproduction (Oxford, England)》2005,20(3):629-635
BACKGROUND: In anovulatory women undergoing ovulation induction, addition of recombinant human LH (rLH) to FSH treatment may promote the dominance of a leading follicle when administered in the late follicular phase. The objective of this study was to find the optimal dose of rLH that can maintain the growth of a dominant follicle, whilst causing atresia of secondary follicles. METHODS: Women with infertility due to anovulation and over-responding to FSH treatment were randomized to receive, in addition to 37.5 IU recombinant human FSH (rFSH), either placebo or different doses of rLH (6.8, 13.6, 30 or 60 microg) daily for a maximum of 7 days. The primary efficacy endpoint was the proportion of patients who had exactly one follicle > or = 16 mm on hCG day. RESULTS: Among 153 enrolled patients, the five treatment groups were similar in terms of baseline characteristics. The proportion of patients with exactly one follicle > or = 16 mm ranged from 13.3% in the placebo group to 32.1% in the 30 microg rLH group (P = 0.048). The pregnancy rate ranged from 10.3% in the 60 microg group to 28.6% in the 30 microg rLH group. Adverse events were similar between groups. CONCLUSIONS: In patients over-responding to FSH during ovulation induction, doses of up to 30 microg rLH/day appear to increase the proportion of patients developing a single dominant follicle (> or = 16 mm). Our data support the 'LH ceiling' concept whereby addition of rLH is able to control development of the follicular cohort. 相似文献
994.
Bokal EV Vrtovec HM Virant Klun I Verdenik I 《Human reproduction (Oxford, England)》2005,20(6):1562-1568
BACKGROUND: The aim of this study was to determine whether, in polycystic ovarian syndrome (PCOS) patients, HCG action prolonged for 4 h improves the action of angiogenic substances [ovarian renin angiotensin system and vascular endothelial growth factor (VEGF)], and consequently follicular maturation, oocyte quality and oocyte fertilization competence. METHODS: In this prospective study 20 patients with PCOS undergoing IVF were included. Oocyte retrieval was carried out either 34 or 38 h after HCG administration. Each follicle was analysed for prorenin, active renin, VEGF and estradiol. Oocytes were evaluated for quality (mature, immature, degenerated oocytes), as were the embryos (low or high). RESULTS: In the HCG +38 h group there were 245 follicles, and in the HCG +34 h group 240 follicles. In the HCG +38 h group, log active renin was lower (2.78 +/- 0.20 versus 2.91 +/- 0.25; P < 0.001) and VEGF higher (2276.0 +/- 790.1 versus 1946.6 +/- 954.5 pg/ml; P < 0.001). The odds ratio for obtaining oocytes from follicles was 1.6 [95% confidence interval (CI) 1.1-2.6; P = 0.02], and for developing high quality embryos 7.6 (95% CI 2.8-20.9; P < 0.001) in favour of the HCG +38 h group. CONCLUSIONS: Follicular maturation and oocyte quality are related to the intrafollicular influences of active renin and VEGF in a time-dependent manner after HCG administration, whereas fertilization competence is related to VEGF only. 相似文献
995.
结缔组织生长因子在单侧输尿管梗阻大鼠肾组织中的表达 总被引:7,自引:3,他引:7
目的:检测大鼠单侧输尿管梗阻(UUO)模型不同时期,肾组织中结缔组织生长因子(CTGF)、转化生长因子β1(TGF-β1)和α-平滑肌肌动蛋白(α-SMA)的表达,观察比较在间质纤维化不同阶段,3者的动态变化及关系。 方法: 采用雄性SD大鼠36只,分为假手术组和模型组,模型组行左侧输尿管结扎术,再分3、7、14、21和28 d共6组,每组6只,于各时点处死大鼠,取肾组织,常规HE、Masson染色,按小管间质损害的特征进行半定量评分。免疫组化检测CTGF、TGF-β1和α-SMA表达。 结果: 随梗阻时间的延长,小管间质纤维化加重,28 d间质已基本被纤维化组织所代替。随间质纤维化程度的加重,CTGF和α-SMA表达逐渐增加,两者与小管间质损害积分呈正相关,CTGF与α-SMA的表达之间也呈正相关。TGF-β1表达在7-14 d达高峰后,逐渐减少,但仍高于对照组。 结论: UUO致CTGF表达增加可能与TGF-β升高有关,CTGF可能通过促进间质中肌成纤维细胞的形成而参与肾间质纤维化。 相似文献
996.
Calcitonin-gene-related peptide (CGRP) is a 37 amino acid neuropeptide synthesized primarily in dorsal root ganglia (DRG) and distributed widely in the perivascular nerves, suggesting that this peptide may play a role in the regulation of peripheral vascular tone. Since female sex steroid hormones have been implicated in the regulation of peripheral vascular tone during pregnancy, we postulated that they may alter the concentration of CGRP in the circulation and thus modulate the increased blood flow observed during pregnancy. In the present study, we measured changes in plasma concentrations of CGRP in non-pregnant, pregnant, and post-partum rats. Groups of ovariectomized rats were treated s.c. for 3 days either with 17beta-oestradiol (2.5 microg per injection twice daily), progesterone (2 mg per injection twice daily), or vehicle. Another group of adult, non-pregnant rats at dioestrus stage of the oestrous cycle was also used in this study. Plasma concentrations of CGRP were higher (P < 0.05) in rats on day 19 of pregnancy (22.0 +/- 3.0 pmol/l) compared to that during delivery (5. 0 +/- 2.0), post-partum day 2 (2.0 +/- 0.7) or in non-pregnant (4.9 +/- 1.6) state. Furthermore, in adult ovariectomized (6.0 +/- 0.6) rats, plasma CGRP concentrations were increased significantly (P < 0. 05) by oestradiol (10.0 +/- 1.0), progesterone (9.5 +/- 1.0) and oestradiol + progesterone (14.0 +/- 1.0). Thus, circulating concentrations of CGRP are elevated during pregnancy and by oestrogen and progesterone, suggesting that the elevated concentrations of CGRP may play an important role in vascular adaptations that occur during pregnancy. 相似文献
997.
Kiseleva EP Krylov AV Lyudyno VI Suvorov AN 《Bulletin of experimental biology and medicine》2005,139(5):576-579
Vascular endothelial growth factor is not only angiogenic, but also immunoregulatory factor. For evaluation of the possibility of its direct interaction with mouse thymocytes we studied the effect of vascular endothelial growth factor on proliferation and apoptosis of thymocytes and expression of genes for the corresponding receptor on these cells. Vascular endothelial growth factor modulated mitogen-induced proliferation of thymocytes and stimulated spontaneous apoptosis in intact thymus cells. Thymocytes express mRNA of type 2, but not type 1 vascular endothelial growth factor receptors.__________Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 139, No. 5, pp. 533–537, May, 2005 相似文献
998.
Type 1 and type 2 tumor infiltrating effector cell subpopulations in progressive breast cancer 总被引:4,自引:0,他引:4
Effector T cells fall into two subpopulations based on cytokine-secretion. Type 1 cells secrete IFN-gamma, whereas type 2 cells secrete IL-4, IL-10, and GM-CSF. NKT cells represent a third subpopulation that secretes similar cytokines and have been associated with immunoregulation. Using the TS/A adenocarcinoma, we assessed the phenotype and kinetics of tumor-infiltrating lymphocytes (TIL) in mice challenged subcutaneously in the mammary region. Flow cytometric analysis shows that T cells do not infiltrate the primary tumor site until days 7-14 following tumor challenge. Both CD4 and CD8 TILs were predominantly CD44(High) and expressed CD25, CD69, and CD95 cell surface activation markers. Activated CD4/CD44(High) TIL numbers reached peak levels at day 21 that precipitously decreased by day 28 whereas corresponding CD8 cell numbers progressively increased, however, at lower levels and with later kinetics. Intracellular cytokine staining showed that greater numbers of IL-4-producing Th2 cells were elicited and with earlier kinetics than that of IFN-gamma-producing Th1 cells. T cells co-expressing DX5 (CD3(+)/DX5(+)) emerged (>21 days), suggesting a recruitment of NK-like T cells at later stages of tumor progression. Moreover, tumors selectively up-regulated TGF-beta, MIF, and IP-10 gene expression at times as early as day 4, with peak levels at day 7 in vivo. Such gene expression remained elevated and correlated with a continued progression in tumor growth suggesting that preferential effector cell recruitment and production of select factors during different stages of tumor maturation may aid in regulating effective endogenous antitumor responses in progressive breast cancer. 相似文献
999.
Yuji Oto Nobuyuki Murakami Keiko Matsubara Sohei Saima Hiroyuki Ogata Hiroshi Ihara Toshiro Nagai Tomoyo Matsubara 《American journal of medical genetics. Part A》2020,182(4):659-663
It is unclear whether hypothyroidism is present in patients with Prader–Willi syndrome (PWS). This study aimed to clarify the state of the hypothalamic–pituitary–thyroid axis and the effects of growth hormone (GH) treatment on thyroid function in pediatric patients with PWS. We retrospectively evaluated thyroid function in 51 patients with PWS before GH treatment using a thyroid‐releasing hormone (TRH) stimulation test (29 males and 22 females; median age, 22 months). We also evaluated the effect of GH therapy on thyroid function by comparing serum free triiodothyronine (fT3), free thyroxine (fT4), and thyroid stimulating hormone (TSH) levels at baseline, 1 year, and 2 years after GH therapy. TSH, fT4, and fT3 levels were 2.28 μU/ml (interquartile range [IQR]; 1.19–3.61), 1.18 ng/dl (IQR; 1.02–1.24), and 4.02 pg/dl (IQR; 3.54–4.40) at baseline, respectively. In 49 of 51 patients, the TSH response to TRH administration showed a physiologically normal pattern; in two patients (4.0%), the pattern suggested hypothalamic hypothyroidism (delayed and prolonged TSH peak after TRH administration). TSH, fT4, and fT3 levels did not change significantly during 1 or 2 years after GH treatment. The TSH response to TRH showed a normal pattern in most patients, and thyroid function did not change significantly during the 2 years after initiating GH treatment. 相似文献
1000.
Biomechanical Properties of Esophagus during Systemic Treatment with Epidermal Growth Factor in Rats
Zhao J Yang J Vinter-Jensen L Zhuang F Gregersen H 《Annals of biomedical engineering》2003,31(6):700-709
The epidermal growth factor (EGF) is a growth factor with effects on many cell types and tissue. Morphometric and passive biomechanical properties were studied in isolated segments of the esophagus in 22 EGF-treated rats and 12 control rats. The rats were divided into groups with EGF treatment for 2, 4, 7, and 14 days (n=6 for each group except n=4 for the 14 days EGF-treatment group) or saline treatment (n=3 for each group). The mechanical test was performed as a distension experiment in vitro where the whole esophagus was stretched to its in situ length and distended with pressures up to 10 cm H2O using a ramp distension protocol. The pressure and outer diameter were recorded. Circumferential stress (force per area) and strain (deformation) were computed from the diameter and pressure data using the zero-stress state as reference. The zero-stress state was obtained by cutting esophageal rings radially. This caused the rings to open up into a sector. EGF induced pronounced morphometric changes, e.g., the wall thickness, wall cross-sectional area, and inner and outer circumferential lengths significantly increased during the EGF treatment. Histological analysis showed mucosa and submucosa growth during EGF treatment. The opening angle and residual strains increased with the highest value in the 14 days EGF-treated group (P < 0.05). The change in opening angle depended largely on the change in mucosa thickness. Furthermore, the circumferential stiffness of the esophagus reached a maximum after 7 days EGF treatment (P < 0.01). © 2003 Biomedical Engineering Society.
PAC2003: 8719Rr, 8717Ee 相似文献