全文获取类型
收费全文 | 1692621篇 |
免费 | 126247篇 |
国内免费 | 3777篇 |
专业分类
耳鼻咽喉 | 21730篇 |
儿科学 | 55634篇 |
妇产科学 | 46151篇 |
基础医学 | 241205篇 |
口腔科学 | 48736篇 |
临床医学 | 151302篇 |
内科学 | 333483篇 |
皮肤病学 | 38654篇 |
神经病学 | 131134篇 |
特种医学 | 63868篇 |
外国民族医学 | 242篇 |
外科学 | 257220篇 |
综合类 | 38945篇 |
现状与发展 | 4篇 |
一般理论 | 531篇 |
预防医学 | 124223篇 |
眼科学 | 40211篇 |
药学 | 123592篇 |
7篇 | |
中国医学 | 4475篇 |
肿瘤学 | 101298篇 |
出版年
2021年 | 12782篇 |
2019年 | 13521篇 |
2018年 | 19950篇 |
2017年 | 15213篇 |
2016年 | 16613篇 |
2015年 | 18957篇 |
2014年 | 26212篇 |
2013年 | 37940篇 |
2012年 | 52724篇 |
2011年 | 55415篇 |
2010年 | 32769篇 |
2009年 | 30692篇 |
2008年 | 51514篇 |
2007年 | 54794篇 |
2006年 | 55255篇 |
2005年 | 52535篇 |
2004年 | 50737篇 |
2003年 | 48147篇 |
2002年 | 46368篇 |
2001年 | 91782篇 |
2000年 | 93605篇 |
1999年 | 76959篇 |
1998年 | 19717篇 |
1997年 | 17268篇 |
1996年 | 17391篇 |
1995年 | 16742篇 |
1994年 | 15289篇 |
1993年 | 14071篇 |
1992年 | 57381篇 |
1991年 | 55270篇 |
1990年 | 52970篇 |
1989年 | 50747篇 |
1988年 | 46131篇 |
1987年 | 44937篇 |
1986年 | 42226篇 |
1985年 | 39987篇 |
1984年 | 29348篇 |
1983年 | 24908篇 |
1982年 | 13898篇 |
1979年 | 25529篇 |
1978年 | 17574篇 |
1977年 | 14906篇 |
1976年 | 13874篇 |
1975年 | 14563篇 |
1974年 | 17630篇 |
1973年 | 16944篇 |
1972年 | 15673篇 |
1971年 | 14453篇 |
1970年 | 13431篇 |
1969年 | 12517篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
Angiogenesis induction and regression in human surgical wounds 总被引:2,自引:0,他引:2
Nicola J. Brown PhD ; Edward A. E. Smyth Bmedsci ; Simon S. Cross MD ; Malcolm W. R. Reed MD 《Wound repair and regeneration》2002,10(4):245-251
Angiogenesis in human wound healing is not well characterized, with only sparse information available regarding the maturation and fate of vessels formed as a consequence of human tissue repair. Therefore, this study aimed to establish the temporal profile of angiogenesis in human dermal wounds. Punch biopsies were obtained under local anesthesia from 45 patients following breast surgery. Scars were predominantly between 2 and 52 weeks after surgery but in five patients were > 52 weeks. Control samples were taken from breast skin peroperatively (n = 24). Quantification of vascular density was performed using the Chalkley grid, following antibody staining for platelet endothelial cell adhesion molecule. Vascular patterns, wound cellularity and morphology were also determined. Cumulative microvessel density was increased in all samples when compared to controls (p < 0.05). This was greatest 2 to 24 weeks following surgery 17 (15-21) median (range), decreased thereafter, but remained elevated compared to controls even in the mature scars > 52 weeks. Control tissue showed an ordered morphological arrangement of dermal structures, collagen, and elastic fibers. However, wounding resulted in marked structural distortion for up to 15 weeks. In conclusion, this study shows for the first time the prolonged persistence of both microvessels and cellularity (fibroblastic cells), in addition to structural distortion in human dermal wounds, which is in contrast to previous in vitro and in vivo studies. 相似文献
995.
Katherine A Hillman Tanya M Johnson Paul J D Winyard Geoffrey Burnstock Robert J Unwin Adrian S Woolf 《Experimental nephrology》2002,10(1):34-42
BACKGROUND: Purinergic receptors are cell-surface molecules that bind extracellular nucleotides, notably ATP. The P2X family includes seven nonselective ion channels with one member, P2X(7), implicated in cytolytic pore formation and cell death. MATERIALS AND METHODS: We sought P2X(7) expression in mouse nephrogenesis and cpk/cpk renal cyst growth, conditions in which both proliferation and apoptosis are prominent. RESULTS: P2X(7) immunolocalized to condensed metanephric mesenchyme: both proliferation and apoptosis were detected in this compartment, assessed by proliferating cell nuclear antigen expression and propidium iodide-stained pyknotic nuclei respectively. Later in nephrogenesis, P2X(7) was detected in collecting ducts, a pattern persisting to maturity. A mesenchymal to epithelial shift of P2X(7) expression was also documented in ureter development. In cpk/cpk kidneys, P2X(7)-expressing collecting duct cysts dominated histology from two weeks until four weeks after birth, when animals die from uremia. In polycystic kidneys pyknotic nuclei were rarely identified in P2X(7)-expressing epithelia, but were detected between cysts, consistent with a non-apoptotic role for P2X(7) in cyst enlargement. CONCLUSION: P2X(7) is expressed during normal nephrogenesis and in a model of congenital polycystic kidney disease. Further experiments are necessary to define possible functions of P2X(7) in these settings. 相似文献
996.
997.
The study of the effects of morphogenesis at puberty on the Leydig cells in the testis of the young hedgehog and of the subsequent changes due to the seasonal varisations, has been done. Furthermore, the restorative changes induced by the exogenous hormones in the Leydig cells and the related sex organs of the regressed hedgehogs have also been studied. It was observed that the Leydig cells from the undifferentiated mesenchyme cell-like nature in the young hedgehog, develop into an adult form possessing large number of lipids, a well-developed Golgi apparatus, complex mitochondria and extensive smooth endoplasmic reticulum. The depletion of the lipids and other regression associated changes are found in the interstitial Leydig cells but not in those situated under tunica albuginea and the latter probably function as lipid storing cells during regression. Pituitary extract, either alone or in combination, but not testosterone, could restore completely the structure of the regressed Leydig cells. Similarly, the restoration of the complete process of spermatogenesis and the structure and function of the epididymis in the regressed hedgehog was found to be dependent upon the synergistic action of both testosterone and the gonadotrophic hormones. 相似文献
998.
Prognostic factors in the treatment of hepatocellular carcinoma with transcatheter arterial embolization and arterial infusion. 总被引:8,自引:0,他引:8
Y Yamashita M Takahashi Y Koga R Saito S Nanakawa Y Hatanaka N Sato K Nakashima J Urata K Yoshizumi 《Cancer》1991,67(2):385-391
From January 1986 to December 1988, a prospective trial of transcatheter arterial treatment was carried out for hepatocellular carcinoma (HCC). Two hundred seventy-five patients were included. Okuda's staging system was employed. Patients with Stage I and II HCC were treated by transcatheter arterial embolization (TAE) with a gelatin sponge containing an anti-cancer agent (protocol 1a); a gelatin sponge and iodized oil mixed with an anti-cancer agent (protocol 1b); or iodized oil mixed with an anti-cancer agent (protocol 2). Patients with Stage III HCC were treated with iodized oil with anti-cancer agent (protocol 2). As an exception, patients with an unsuccessful superselective catheterization into the proper hepatic artery by Seldinger technique or obstruction of the main trunk of the portal vein were treated with percutaneous transcatheter arterial infusion into the common hepatic artery regardless of stage (protocol 3). Tumor type and extension, area of tumor involvement, portal vein involvement, method of treatment, and presence of ascites and icterus were found to be the significant factors for an initial response to therapy. Treatment method was the most important factor. Respective survival rates at 1 and 2 years were 70.9% and 55.3% for protocol 1a; 62.3% and 43.8% for protocol 1b; 37.8% and 18.3% for protocol 2; and 16.5% and 0% for protocol 3. Many factors proved to significantly influenced prognosis; however, tumor type had the most important prognostic significance followed by AFP value, ascites, treatment protocol, and area of tumor involvement. 相似文献
999.
1000.
Kaposi's sarcoma. CT-radiographic correlation 总被引:1,自引:0,他引:1
The role of CT in the diagnosis of intrathoracic Kaposi's sarcoma (KS) was evaluated retrospectively in 24 patients, in the absence of coexistent opportunistic infections. In all cases the diagnosis of KS was initially established by histologic evaluation of extrathoracic disease: 15 patients had verified parenchymal KS and nine patients endobronchial KS. (Chest roentgenograms were analyzed separately for each group: in 14 patients serial films were available for review. The predominant radiographic findings was the presence of nonspecific, bilateral, perihilar infiltrates in 22 of 24 cases (92 percent). Corresponding CT scans documented the presence of abnormal hilar densities characteristically extending into the adjacent pulmonary parenchyma along distinctly perivascular and peribronchial pathways. Discrete, poorly marginated nodules were identified radiographically in ten cases (42 percent); these proved to be randomly distributed throughout the parenchyma on CT. Radiographic evidence of mediastinal adenopathy was distinctly unusual, seen in only two cases (8 percent). While CT typically demonstrated shotty adenopathy, significantly enlarged nodes (greater than 1 cm) were rarely identified. We concluded that CT is more specific than routine roentgenograms for identifying pulmonary KS. While not pathognomonic, peribronchial and perivascular disease is sufficiently characteristic to obviate more invasive diagnostic procedures, especially in patients with established KS. 相似文献