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   6575篇
  免费   483篇
  国内免费   45篇
耳鼻咽喉   61篇
儿科学   133篇
妇产科学   102篇
基础医学   1248篇
口腔科学   158篇
临床医学   406篇
内科学   1607篇
皮肤病学   145篇
神经病学   474篇
特种医学   172篇
外科学   1046篇
综合类   26篇
一般理论   3篇
预防医学   278篇
眼科学   169篇
药学   485篇
中国医学   12篇
肿瘤学   578篇
  2023年   54篇
  2022年   123篇
  2021年   231篇
  2020年   120篇
  2019年   163篇
  2018年   193篇
  2017年   148篇
  2016年   137篇
  2015年   195篇
  2014年   206篇
  2013年   253篇
  2012年   403篇
  2011年   395篇
  2010年   255篇
  2009年   209篇
  2008年   383篇
  2007年   390篇
  2006年   340篇
  2005年   384篇
  2004年   344篇
  2003年   297篇
  2002年   274篇
  2001年   149篇
  2000年   143篇
  1999年   120篇
  1998年   69篇
  1997年   52篇
  1996年   41篇
  1995年   31篇
  1994年   33篇
  1993年   26篇
  1992年   82篇
  1991年   85篇
  1990年   75篇
  1989年   93篇
  1988年   80篇
  1987年   66篇
  1986年   55篇
  1985年   54篇
  1984年   55篇
  1983年   46篇
  1982年   18篇
  1981年   20篇
  1980年   17篇
  1979年   27篇
  1978年   22篇
  1977年   20篇
  1976年   12篇
  1972年   14篇
  1970年   18篇
排序方式: 共有7103条查询结果,搜索用时 297 毫秒
11.
Due to the great advancements in fetal ultrasonography, the number of prenatal diagnoses are increasing, greatly contributing to improved neonatal surgery. It is now relatively easy to detect huge fetal cystic masses, and we have experienced three cases with a huge neck tumor detected in utero, one case with teratoma and two cases with cystic hygroma. Each case was complicated by neonatal asphyxia, and the neonate needed resuscitation by means of endotracheal intubation. The infant with teratoma unfortunately died of respiratory distress due to compression of the trachea before a perinatal team could be organized. Although the remaining cases with cystic hygroma were treated by a perinatal team, one died 19 hours after birth and the other has survived with the aid of endotracheal intubation in the hospital for three years. In addition, all four cases of cystic hygroma detected antenatally in our institute, which were not delivered, also had fetal hydrops which suggested a general lymphatic derangement. Cystic hygroma detected in utero is considered to be different from that detected after birth, since the former is associated with genetic lymphatic derangement. Prenatal diagnosis enables such patients to survive the perinatal period, but may not improve the prognosis of fetal cystic hygroma so much.  相似文献   
12.
Plasma levels of plasminogen activators (t-PA, u-PA) and their inhibitor (PAI-1) were studied in patients suffering from Buerger's disease and healthy volunteers before and after 15 minutes of venous occlusion test. The baseline levels of t-PA in group of patients did not differ from those of controls. On the contrary patients with Burger's disease showed a marked increase in u-PA antigen concentrations with concomitant decrease in PAI-1 antigen levels. During venous stasis t-PA antigen concentrations increased in all subjects, however it was much pronounced in controls. Venous occlusion resulted in significant decrease in free PAI-1 levels in the group of patients only. In conclusion, Buerger's disease is associated with the endothelial derangement with increased u-PA release and decreased PAI-1 release, which does not influence the function of fibrinolytic system. The fact that the reduced response of the endothelium to release t-PA after venous stasis goes in parallel with marked decrease in PAI-1 antigen levels seems to suggest that patients suffering from Buerger's disease are not at high risk of intravascular fibrin deposition.  相似文献   
13.
Mouse monoclonal antibodies against human (beta 1-4)galactosyl-transferase (GalT) purified from human ovarian tumor effusion fluids were prepared and characterized. GalT purified from normal human plasma showed a single diffused band in nondenaturing polyacrylamide gel electrophoresis, but GalT purified from human ovarian tumor effusion fluids showed several oligomeric bands and a monomeric band in nondenaturing polyacrylamide gel electrophoresis. These oligomeric bands were dissociated into monomer by urea treatment and polymerized by a 2-mercaptoethanol treatment. Nine monoclonal antibodies (MAb) were prepared by immunization of purified GalT from human ovarian tumor effusion fluids and classified into three groups. Type I MAbs (MAb8611, MAb8913, and MAb8919) reacted only to the GalT monomer. Type II MAbs (MAb4880, MAb8507, and MAb8628) reacted to both the GalT monomer and the GalT polymer. Type III MAbs (MAb7907, MAb8513, and MAb8677) reacted only to the GalT polymer. These MAbs except MAb7907 could recover GalT enzyme activity from effusion fluids by immunoprecipitation. A fraction passed through MAb8513 affinity chromatography still showed reactivity to MAb8919, demonstrating that an epitope of MAb8513 resides on a minor part of GalT. A sandwich immunoassay (MAb8513-MAb8628HRP) was developed, and serum samples from ovarian cancer patients and benign ovarian patients were tested. The levels of sandwich immunoassay of serum samples from cancer were elevated significantly compared to those from benign and did not necessarily correlate to total GalT enzyme activity in serum samples. These results suggested that MAb8513 (Type III) might recognize a unique GalT associated with tumor (GAT).  相似文献   
14.
Changes in water intake after hepatic vagotomy were examined in the body weights of 3 different rats (about 100, 200 and 280 g). The vagotomy reduced water intake only in the 100-g rats.  相似文献   
15.
Samples from seventy autopsy cases ranging from 27 to 79 years of age who had shown no evidence of renal or malignant diseases were examined histologically to clarify renal changes with age. We evaluated scores for renal histological change and referred the scores to clinical laboratory data; blood pressure, complete blood counts (RBC count, hematocrit, hemoglobin), serum chemistry values (creatinine, urea nitrogen, total cholesterol, total protein, sodium, potassium, chloride) and urinalysis (protein, sediment). We found the score to be related to serum creatinine level, blood urea nitrogen level and the degree of hematuria but not related to the other factors. The progression of arteriosclerosis, tubulo-interstitial change and global sclerosis were found to be severe with ageing. Also renal weight decreased with increasing age. However there were great differences among individuals in the extent of changes. We could not assume histological changes were generally severe in those of more than 55-65 years of age. It was impossible to clarify renal states only with clinical findings. Some kidneys had severe histological changes though less than 2.0 mg/dl of serum creatinine level. It suggests that living relatives and cadavers over 60 years old can be donors for renal transplantation when there are no significant findings of abnormality in preoperative evaluations of their physical state. If insufficient examinations are done, we cannot determine which of them will be good donors. Therefore preoperative biopsy is the best way to evaluate donor suitability. To evaluate only clinical data, it is necessary that serum creatinine level be less than 1.2 mg/dl, blood urea nitrogen level be less than 23 mg/dl and there be no hematuria.  相似文献   
16.
To examine the role of the apoptosis of macrophages and smooth muscle cells in the development of atherosclerosis, human aortic tissues with intimal lesions were immunostained with antibodies against terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL), single-stranded DNA (clone F7-26), and active caspase-3. Apoptotic cells were detected in the intima using both TUNEL and single-stranded DNA, however, the latter method was the more sensitive one for detecting apoptotic cells in the early stages of atherosclerosis. The number of apoptotic cells increased as the disease progressed. It implies that the apoptosis of intimal cells is involved in the formation of atherosclerotic lesions. In addition, quantitative analyses of the cell types undergoing apoptosis using double-immunostaining revealed that the susceptibility of macrophages and smooth muscle cells to apoptosis was greater specifically in atheroma than in the other atherosclerotic lesions, and macrophages were more susceptible to apoptosis than smooth muscle cells. The frequency and spatial distribution of oxidized low-density lipoprotein (oxLDL) (FOH1a/DLH3)-positive cells were examined by immunohistochemistry, and the results resembled those of apoptotic cells. The number of oxLDL-positive cells in the intima significantly correlated with the susceptibility of smooth muscle cells, but not with that of macrophages, to apoptosis. These results suggest that oxLDL affects the apoptosis of smooth muscle cells during the atherosclerotic development.  相似文献   
17.
A case of Vibrio cholerae non-O1 septicemia is described in this paper. A 45-year-old male with a three year history of liver cirrhosis, was admitted to our division with hematemesis, abdominal pain, high fever and a loss of consciousness. Three days before onset of symptoms, he traveled to Ishigaki Island and ate a raw lobster. Two days after, his temperature rose to 39.7 degrees C and the blood pressure dropped to 36/- mmHg. By endoscopic examination, an ulcer was found in the stomach, and the bleeding was stopped by electrical coagulation. Blood culture showed growth of V. cholerae non-O1. The organism was found to be sensitive to OFLX, CZX, MINO, LMOX and CP. Although DIC, infections of fungus and MRSA occurred as complications, he recovered by adequate procedures. Subsequently, he left this division after eight weeks. There are various reports related to V. cholerae non-O1 septicemia in foreign countries, but few cases have been reported in Japan. And these cases had severe underlying diseases such as leukemia and liver cirrhosis.  相似文献   
18.
To evaluate prognostic significance of echogenic lesion within small hepatocellular carcinoma (SHCC, less than or equal to 2 cm in diameter), clinical and pathological findings of 32 cases with SHCC containing echogenic lesion (echogenic SHCC) were compared with those of 55 cases with non-echogenic SHCC. Compared with the non-echogenic SHCC group, the frequency of clinical stage I was significantly higher, and there were significantly more cases with solitary tumor relative to cases with multiple tumors in the echogenic SHCC group. Histologically, the incidence of the HCC composed of well-differentiated tumor cells corresponding to Edmondson's grade I was significantly higher in the echogenic SHCC group than in the non-echogenic SHCC group. Although HCCs tended to become progressively less differentiated with increasing tumor sizes in the both groups, the process of cellular change appeared to proceed more slowly in the echogenic SHCC group. Survival rate after tumor detection was 73% at three years, 56% at five years and 48% at seven years and nine years in the echogenic SHCC group, while it was 46% at three years, 42% at five years and 0% at seven years in the non-echogenic SHCC group. The present results showed that the presence of echogenic lesion within SHCC could be useful prognostic indicator.  相似文献   
19.
To characterize apoptosis in keloids and the mechanisms responsible for this process, the expression of activated caspase-9 and -3 in fibroblasts obtained from keloids was analyzed. Immunohistochemistry revealed that the number of fibroblasts positive for terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) or activated caspase-9 or -3 was low but was significantly higher in keloid tissues than in normal scar tissues. Significant relationships between the number of caspase-positive fibroblasts and TUNEL-positive fibroblasts suggested that the activation of caspase-9 and -3 induces apoptosis in a subpopulation of keloid fibroblasts. All keloid fibroblast cell lines established in this study showed activation of caspase-9 and -3 after serum deprivation for 3 or 4 hours, as shown using Western blotting. Furthermore, serum deprivation-induced apoptosis in a keloid fibroblast line was blocked by a caspase-9 inhibitor (acetyl-Leu-Glu-His-Asp-al), indicating that activation of caspase-9 was necessary for the process of apoptosis in keloid fibroblasts. Although serum deprivation did not significantly change the level of apoptosis protease activating factor-1 in any of the lines, cytochrome c release was detected in cytosolic fractions of the lines after serum deprivation for 3 or 4 hours. These results strongly suggest that keloid fibroblasts are predisposed to apoptosis and cytochrome c release and that caspase-9 activation may underlie regulation of apoptosis in keloid fibroblasts in vivo.  相似文献   
20.
Pseudoaneurysm is an uncommon and serious complication of infective endocarditis (IE). It is often fatal because of its rapid progress, high rates of rupture and recurrence, and worsening effects on the systemic condition. We report the rare case of a patient who developed a pseudoaneurysm of the sinus of Valsalva two months after emergency aortic valve replacement for active IE. At the previous operation, we had directly closed a small fistulous hole in the non-coronary sinus of Valsalva using two mattress sutures with autologous pericardial pledgets, because the tissue surrounding the hole did not appear to be infected on visual inspection. A pseudoaneurysm developed from this portion due to detachment of sutures. If the fistula had been completely resected during the first surgery instead of performing a simple closure, the pseudoaneurysm of the sinus of Valsalva would not have formed. However, the primary aim of the first emergency surgery was to spare the life of a critically ill patient. In the second surgery, the pseudoaneurysm was completely resected with the aortic wall--including the non-coronary sinus of Valsalva and the communicating hole. Then, patch plasty of the non-Valsalva sinus was successfully performed.  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