全文获取类型
收费全文 | 1379篇 |
免费 | 52篇 |
专业分类
1431篇 |
出版年
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 14篇 |
2016年 | 22篇 |
2015年 | 32篇 |
2014年 | 24篇 |
2013年 | 117篇 |
2012年 | 66篇 |
2011年 | 67篇 |
2010年 | 39篇 |
2009年 | 44篇 |
2008年 | 71篇 |
2007年 | 75篇 |
2006年 | 82篇 |
2005年 | 74篇 |
2004年 | 89篇 |
2003年 | 77篇 |
2002年 | 59篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 30篇 |
1998年 | 25篇 |
1997年 | 27篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 12篇 |
1990年 | 17篇 |
1989年 | 20篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 18篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 15篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1968年 | 7篇 |
排序方式: 共有1431条查询结果,搜索用时 0 毫秒
41.
Although the role of PTH (parathyroid hormone) has been debated in glucocorticoid (GC)-induced osteoporosis (GIO), clinical data about the relation of endogenous PTH to bone metabolism in patients treated with GC are still lacking. The present study was performed to examine the relationship of PTH to bone metabolic indices, bone mineral density (BMD), and bone geometry in 174 female patients treated with oral GC for more than 6 months. Dual-energy X-ray absorptiometry and peripheral quantitative computed tomography (pQCT) were employed for the assessment of BMD and bone geometry. No elevation of serum PTH levels was observed in patients treated with GC. Although serum levels of osteocalcin were not related to serum PTH levels, urinary levels of deoxypiridinoline were positively correlated. Serum PTH levels were negatively related to BMD at any site. In pQCT, serum PTH levels were negatively correlated to both trabecular and cortical volumetric BMD. As for bone morphometric indices, serum PTH levels were significantly related to endocortical circumferences, cortical thickness, and cortical area. Moreover, serum PTH levels were significantly higher in patients with vertebral fractures, compared with those without vertebral fractures in GC-treated patients. In the present study, serum PTH levels were related to the elevation of bone resorption marker, decreased BMD, cortical thinning, and an increase of vertebral fracture risk. The elevation of sensitivity to PTH in bone might play some role in the pathogenesis of GIO. 相似文献
42.
Ikeda Y Yonemitsu Y Kataoka C Kitamoto S Yamaoka T Nishida K Takeshita A Egashira K Sueishi K 《American journal of physiology. Heart and circulatory physiology》2002,283(5):H2021-H2028
Monocyte/macrophage chemoattractant protein-1 (MCP-1), a potent chemoattractant chemokine and an activator for mononuclear cells, may play a role in the initiation and/or progression of pulmonary hypertension (PH). To determine whether blockade of a systemic MCP-1 signal pathway in vivo may prevent PH, we intramuscularly transduced a naked plasmid encoding a 7-NH(2) terminus-deleted dominant negative inhibitor of the MCP-1 (7ND MCP-1) gene in monocrotaline-induced PH. We also simultaneously gave a duplicate transfection at 2-wk intervals or skeletal muscle-directed in vivo electroporation (EP) to evaluate whether a longer or higher expression might be more effective. The intramuscular reporter gene expression was enhanced 10 times over that by EP than by simple injection, and a significant 7ND MCP-1 protein in plasma was detected only in the EP group. 7ND MCP-1 gene transfer significantly inhibited the progression of MCT-induced PH as evaluated by right ventricular systolic pressure, right ventricular hypertrophy, medial hypertrophy of pulmonary arterioles, and mononuclear cell infiltration into the lung. Differential effects of longer or higher transgene expression were not apparent. Although the in vivo kinetics of 7ND MCP-1 gene therapy should be studied further, these encouraging results suggest that an anti-inflammatory strategy via blockade of the MCP-1 signal pathway may be an alternative approach to treat subjects with PH. 相似文献
43.
A remarkable increase in the production of superoxide radicals and SOD activity was measured in suspension of the murine macrophage cell line C4M phi treated with Lentinan (4-10 X 10(3) micrograms/5 X 10(6) cells). In activated macrophages the decrease of lipid peroxidation could be interpreted as a consequence of enhanced SOD activity. 相似文献
44.
When human diploid fibroblasts IMR-90 are cultured in routinely used medium (Eagle's basal medium supplemented with 10% fetal calf serum), sulfhydryl compounds appear in the medium. The major component of these sulfhydryl compounds is cysteine, and it is shown that a part of medium cystine is converted into cysteine by the cells. It is also shown that the sulfhydryl groups of serum albumin, which are masked and barely detectable before the culture, are restored. Probably cysteine formed by the cells reacts with serum albumin to give rise to the protein sulfhydryl groups via sulfhydryl–disulfide exchange reactions. Total sulfhydryl concentrations in the medium are maintained in a considerable level throughout the culture, and a possible physiological function of these sulfhydryl groups is discussed. 相似文献
45.
Hideo Inoue Shiro Koizume Takahiro Yamauchi Kouichi Murata Eiko Ohtsuka 《Nucleosides, nucleotides & nucleic acids》2013,32(7-9):1489-1490
Abstract Permanganate reaction of DNA oligomers containing an 8-oxoadenine or 5hydroxyuracil residue was studied, and the results were compared with those for an 8-oxoguanine-containing oligomers. We obtained similar results and found that the nucleotide residues neighboring the modified base were damaged and that the novel damage was induced by the oxidation of the modified base. 相似文献
46.
Tae Mogami Naho Yokota Mikiko Asai-Sato Roppei Yamada Shiro Koizume Yuji Sakuma Mitsuyo Yoshihara Yoshiyasu Nakamura Yasuo Takano Fumiki Hirahara Yohei Miyagi Etsuko Miyagi 《PloS one》2013,8(11)
Ovarian clear cell adenocarcinoma (CCC) is the second most common subtype of ovarian cancer after high-grade serous adenocarcinomas. CCC tends to develop resistance to the standard platinum-based chemotherapy, and has a poor prognosis when diagnosed in advanced stages. The ANXA4 gene, along with its product, a Ca++-binding annexin A4 (ANXA4) protein, has been identified as the CCC signature gene. We reported two subtypes of ANXA4 with different isoelectric points (IEPs) that are upregulated in CCC cell lines. Although several in vitro investigations have shown ANXA4 to be involved in cancer cell proliferation, chemoresistance, and migration, these studies were generally based on its overexpression in cells other than CCC. To elucidate the function of the ANXA4 in CCC cells, we established CCC cell lines whose ANXA4 expressions are stably knocked down. Two parental cells were used: OVTOKO contains almost exclusively an acidic subtype of ANXA4, and OVISE contains predominantly a basic subtype but also a detectable acidic subtype. ANXA4 knockdown (KO) resulted in significant growth retardation and greater sensitivity to carboplatin in OVTOKO cells. ANXA4-KO caused significant loss of migration and invasion capability in OVISE cells, but this effect was not seen in OVTOKO cells. We failed to find the cause of the different IEPs of ANXA4, but confirmed that the two subtypes are found in clinical CCC samples in ratios that vary by patient. Further investigation to clarify the mechanism that produces the subtypes is needed to clarify the function of ANXA4 in CCC, and might allow stratification and improved treatment strategies for patients with CCC. 相似文献
47.
Background
Although pancreatic ductal adenocarcinoma is characterized by an abundant stroma enriched with hyaluronan (HA), the prognostic impact of HA and its regulators remains unknown.Methods
Using immunohistochemistry, expression patterns of HA and its regulators, including a synthesizing enzyme (HAS2), and a degrading enzyme (HYAL1) were investigated in patients who received surgical resection. The prognostic significance of these markers and other clinicopathological variables was determined using univariate and multivariate analyses. The HA levels were determined quantitatively by enzyme-linked immunosorbent assay (ELISA).Results
We found that strong expressions of HA (P=0.008) and HAS2 (P=0.022) were significantly associated with shorter survival time after surgery. By contrast, weak expression of HYAL1 was significantly associated with poor survival (P=0.001). In multivariate analysis, tumor stage (hazard ratio (HR)=2.76, 95% confidence interval (CI): 1.14-6.66 P=0.024), strong HA expression (HR=6.04, 95%CI: 1.42-25.69 P=0.015), and weak HYAL1 expression (HR=3.16, 95%CI: 1.19-8.40 P=0.021) were independent factors predicting poor survival. ELISA revealed higher concentration of HA in pancreatic cancer tissues than in normal pancreatic tissues (P=0.001).Conclusion
These findings suggest, for the first time, that HA and its regulators may have prognostic impact in patients with pancreatic cancer. 相似文献48.
Kiyoshi Migita Toru Arai Naoki Ishizuka Yuka Jiuchi Yasuharu Sasaki Yasumori Izumi Tetsuyuki Kiyokawa Eiichi Suematsu Tomoya Miyamura Hiroshi Tsutani Yojiro Kawabe Ryutaro Matsumura Shunsuke Mori Shiro Ohshima Shigeru Yoshizawa Kenji Kawakami Yasuo Suenaga Hideo Nishimura Toyohiko Sugimoto Hiroaki Iwase Hideyuki Sawada Haruhiro Yamashita Shigeyuki Kuratsu Fumitaka Ogushi Masaharu Kawabata Toshihiro Matsui Hiroshi Furukawa Seiji Bito Shigeto Tohma 《PloS one》2013,8(11)
Background/Aims
The Japanese National Hospital Organization evidence-based medicine (EBM) Study group for Adverse effects of Corticosteroid therapy (J-NHOSAC) is a Japanese hospital-based cohort study investigating the safety of the initial use of glucocorticoids (GCs) in patients with newly diagnosed autoimmune diseases. Using the J-NHOSAC registry, the purpose of this observational study is to analyse the rates, characteristics and associated risk factors of intracellular infections in patients with newly diagnosed autoimmune diseases who were initially treated with GCs.Methodology/Principal Findings
A total 604 patients with newly diagnosed autoimmune diseases treated with GCs were enrolled in this registry between April 2007 and March 2009. Cox proportional-hazards regression was used to determine independent risk factors for serious intracellular infections with covariates including sex, age, co-morbidity, laboratory data, use of immunosuppressants and dose of GCs. Survival was analysed according to the Kaplan-Meier method and was assessed by the log-rank test. There were 127 serious infections, including 43 intracellular infections, during 1105.8 patient-years of follow-up. The 43 serious intracellular infections resulted in 8 deaths. After adjustment for covariates, diabetes (Odds ratio [OR]: 2.5, 95% confidence interval [95% CI] 1.1–5.9), lymphocytopenia (≦1000/μl, OR: 2.5, 95% CI 1.2–5.2) and use of high-dose (≧30 mg/day) GCs (OR: 2.4, 95% CI 1.1–5.3) increased the risk of intracellular infections. Survival curves showed lower intracellular infection-free survival rate in patients with diabetes, lymphocytopaenia and high-dose GCs treatments.Conclusions/Significance
Patients with newly diagnosed autoimmune diseases were at high risk of developing intracellular infection during initial treatment with GCs. Our findings provide background data on the risk of intracellular infections of patients with autoimmune diseases. Clinicians showed remain vigilant for intracellular infections in patients with autoimmune diseases who are treated with GCs. 相似文献49.