全文获取类型
收费全文 | 3267篇 |
免费 | 11篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 106篇 |
金属工艺 | 4篇 |
机械仪表 | 12篇 |
建筑科学 | 27篇 |
矿业工程 | 1篇 |
能源动力 | 3篇 |
轻工业 | 39篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 107篇 |
一般工业技术 | 69篇 |
冶金工业 | 2776篇 |
原子能技术 | 17篇 |
自动化技术 | 101篇 |
出版年
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 17篇 |
2012年 | 8篇 |
2011年 | 21篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 16篇 |
2007年 | 21篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 16篇 |
2001年 | 17篇 |
2000年 | 21篇 |
1999年 | 102篇 |
1998年 | 809篇 |
1997年 | 480篇 |
1996年 | 306篇 |
1995年 | 174篇 |
1994年 | 175篇 |
1993年 | 179篇 |
1992年 | 49篇 |
1991年 | 48篇 |
1990年 | 57篇 |
1989年 | 80篇 |
1988年 | 52篇 |
1987年 | 52篇 |
1986年 | 37篇 |
1985年 | 45篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 17篇 |
1981年 | 27篇 |
1980年 | 33篇 |
1979年 | 7篇 |
1978年 | 13篇 |
1977年 | 65篇 |
1976年 | 141篇 |
1975年 | 10篇 |
1973年 | 10篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 6篇 |
1964年 | 3篇 |
排序方式: 共有3278条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
Malcolm Goodman 《Creativity & Innovation Management》2000,9(1):46-53
Many organisations are under pressure as they face strong buyers’ markets. This paper presents the findings of a research project designed to discover why talent is so often frustrated by mediocre management and what might be done about it. ICI and Marks & Spencer were selected as the setting, as both are well‐respected corporations and are facing stiff business challenges. The paper explores the locking hold that cultures can exert on operational management. It opens with a profile of each organisation before passing the consultancy brief to an imaginary business detective, Sherlock Holmes. By means of various devices the famous detective applies his powers to the case and the paper closes with a summary of his findings. 相似文献
105.
Scott Dam is owned and operated by Pacific Gas & Electric Co. (PG&E) as part of the Potter Valley Project. Although it is an unimpressive concrete gravity dam [233 m (765 ft) long with maximum water surface 33.4 m (110 ft) above tailwater], the dam has unusually complex and weak foundation rocks; this condition caused design changes during construction, numerous subsequent special investigations, and several corrections and additions. A main stumbling block to clarification of the dam safety issue for Scott Dam has always been difficulty in characterizing the foundation material. This paper discusses an approach to this problem as well as how the safety of the dam was subsequently confirmed, following a comprehensive program of research, investigations, and analysis from 1991 to 1997. 相似文献
106.
The use of imaging studies in the diagnosis and management of thyroid cancer and hyperparathyroidism
With the variety of radiopharmaceutical agents and refined imaging techniques, thyroid and parathyroid imaging provides much valuable clinical information. The use of imaging is most important in the follow-up of differentiated (DTC) and medullary thyroid cancer (MTC). Patients with DTC are followed with serum thyroidglobulin and 131I whole body scintigraphy when the serum thyroglobulin level is elevated. When the 131I scintigram is negative, 201Tl scintigraphy may best identify the site of recurrent DTC. Alternative radioisotopes, ultrasound, CT, and FDG PET are also useful in localizing the site of DTC metastases. MTC recurrences and metastases are more difficult to image. Selective venous catheterization is the most sensitive and specific method for detecting areas of recurrent MTC. High-resolution ultrasound, CT, MR imaging, and scintigraphy are all capable of, and useful in, detecting macroscopic foci of metastatic tumor. Somatostatin receptor scintigraphy and 99mTc DMSA have been the most frequently used nuclear imaging agents in patients with recurrent MTC. Imaging for hyperparathyroidism remains controversial. Sestambi has become the preferred isotope for parathyroid scintigraphy; whereas high-resolution ultrasound is also frequently used. Preoperative imaging is being used as a method to allow a unilateral neck exploration, more recently, in conjunction with intraoperative 1-84 PTH assay and with intraoperative use of the gamma probe. Most often, parathyroid imaging is performed before reoperation for persistent hyperparathyroidism. 相似文献
107.
Spontaneous hematomas are rare and can present with acute or chronic symptoms. Our patient presented with deep vein thrombosis of the lower extremity associated with a spontaneous pelvic hematoma. This lesion was radiologically and clinically indistinguishable from a soft-tissue neoplasm. The case of a spontaneous pelvic neoplasm in an otherwise healthy young man is presented and the literature reviewed regarding issues of differential diagnosis and clinical management. 相似文献
108.
DC Park C Hertzog H Leventhal RW Morrell E Leventhal D Birchmore M Martin J Bennett 《Canadian Metallurgical Quarterly》1999,47(2):172-183
OBJECTIVES: To create a profile of individuals nonadherent to their medications in an age-stratified sample (ages 34-84) of community-dwelling rheumatoid arthritis patients. The relative contributions of age, cognitive function, disability, emotional state, lifestyle, and beliefs about illness to nonadherence were assessed. DESIGN: A direct observation approach was used in conjunction with structural equation modeling. All participants were administered a preliminary assessment battery. Medications were then transferred to vials with microelectronic caps that recorded medication events for all medications for the next 4 weeks. PARTICIPANTS AND SETTING: A volunteer sample of 121 community-dwelling rheumatoid arthritis (RA) patients were recruited from newspaper ads, posters, and via informal physician contact from private rheumatology practices in Atlanta and Athens, Georgia. Written verification of the RA diagnosis and a disease severity rating were obtained from personal physicians before patients were enrolled in the study. Patients were tested in a private physician's office, and their medication adherence was monitored electronically for a month in their every-day work and home settings. MEASUREMENTS AND RESULTS: Structural equation modeling techniques were used to develop a model of adherence behavior. Cognitive and psychosocial measures were used to construct latent variables to predict adherence errors. The model of medication adherence explained 39% of the variance in adherence errors. The model demonstrated that older adults made the fewest adherence errors, and middle-aged adults made the most. A busy lifestyle, age, and cognitive deficits predicted nonadherence, whereas coping with arthritis-related moods predicted adherence. Illness severity, medication load, and physical function did not predict adherence errors. Omission of medication accounted for nearly all errors. CONCLUSION: Despite strong evidence for normal, age-related cognitive decline in this sample, older adults had sufficient cognitive function to manage medications. A busy lifestyle and middle age were more determinant of who was at risk of nonadherence than beliefs about medication or illness. Thus, practicing physicians should not assume that older adults have insufficient cognitive resources to manage medications and that they will be the most likely to make adherence errors. Very busy middle-aged adults seem to be at the greatest risk of managing medications improperly. 相似文献
109.
JV Fleming P Barrett SL Coon DC Klein PJ Morgan 《Canadian Metallurgical Quarterly》1999,140(2):972-978
The enzyme arylalkylamine N-acetyltransferase (AANAT; EC 2.3.1.87) has been conventionally linked with the biosynthesis of melatonin within the pineal gland and retina. This study establishes that AANAT messenger RNA (mRNA) and functional enzyme occurs within the pars tuberalis (PT) and to a lesser degree within the pars distalis (PD) of the sheep pituitary gland; expression in these tissues is approximately 1/15th (PT) and 1/300th (PD) of that in the ovine pineal gland. AANAT mRNA in the PT appears to be expressed in the same cells as the Mel1a receptor. No evidence was obtained to indicate that either PT or PD cells have the ability to synthesize melatonin, suggesting that this enzyme plays a different functional role in the pituitary. We also found that cAMP regulation of the abundance of AANAT mRNA differs between the PT and pineal gland. Forskolin (10 microM) has no effect on pineal AANAT mRNA levels, yet represses expression in the PT. This suppressive influence could be mediated by ICER (inducible cAMP response early repressor), which is induced by forskolin in both tissues. Although it appears that the specific function and regulation of AANAT in the pituitary gland differ from that in the pineal gland, it seems likely that AANAT may play a role in the broader area of signal transduction through the biotransformation of amines. 相似文献
110.
PURPOSE: We identified the incidence and types of genital and urinary anomalies, and established a plan for evaluating the urinary system in the CHARGE association. MATERIALS AND METHODS: We retrospectively reviewed the charts of 32 patients in whom the CHARGE association was diagnosed. RESULTS: Of the 32 patients identified 22 (69%) had genitourinary abnormalities. Genital anomalies, including micropenis, penile agenesis, hypospadias, chordee, cryptorchidism, a bifid scrotum, atresia of the uterus, cervix and vagina, and hypoplastic labia majora, labia minora and clitoris, were present in 18 patients (56%). Of the 24 patients who underwent renal ultrasound 10 (42%) were diagnosed with urinary tract anomalies including a solitary kidney, hydronephrosis, renal hypoplasia and duplex kidneys. Further evaluation revealed vesicoureteral reflux, neurogenic bladder secondary to spinal dysraphism, nephrolithiasis, ureteropelvic junction obstruction and a nonfunctioning upper pole in both duplex kidneys. CONCLUSIONS: There is a high incidence of genitourinary anomalies in the CHARGE association. Because of this high incidence of anomalies, patients with this condition should undergo a careful genitourinary evaluation, including renal and bladder ultrasound, and voiding cystourethrography screening. 相似文献